Welcome to the era of immortalists: scientists, dreamers and – crucially – billionaires, who want us to think of age as a curable disease, and our final end as something that could be indefinitely postponed. According to one estimate, the revenues of the global anti-ageing industry will increase from about $200bn today to $420bn by 2030. One sure sign of its rosy prospects is the involvement of high-profile people in the US who have made vast fortunes from the internet. If many of them can avoid taxes, why not death?

“Death is sort of an affront to American life,” wrote Zadie Smith in 2003. “It’s so anti-aspirational.” In tech circles, this kind of distaste for mortality often blurs into the culture of “biohacking” (fasting, closely tracking your vital signs, gobbling supplements and “smart drugs”) which is one manifestation of transhumanism: to quote the definition in the Oxford English Dictionary, “a belief that the human race can evolve beyond its current limitations, especially by the use of science and technology”.

The sums invested in anti-ageing research by such tech players as the Google founders, Larry Page and Sergey Brin, and the Trump-supporting venture capitalist, Peter Thiel, show what happens when such ideas meet big money. The same goes, somewhat predictably, for the activities of the Amazon founder and aspiring astronaut, Jeff Bezos, who has previously funded an anti-ageing setup called Unity Biotechnology, and, via his personal investment vehicle Bezos Expeditions, is now reportedly a donor to a newly founded California venture called Altos Labs. The latter company is apparently going to set up “institutes” in the US, the UK and Japan, and is recruiting scientists with the offer of big salaries. One insider says its initial aim is to “understand rejuvenation”; its focus is the kind of “biological reprogramming technology” focused on the manipulation of cells.

Plenty of other companies – they have such names as BioViva, Youthereum Genetics, the Longevity Fund and AgeX Therapeutics – are also trying to somehow arrest ageing. Piercing through the research and journalism that surrounds what they are doing, you occasionally get the vague feeling that some of the people involved may eventually come across some or other revelation about age-related diseases, but there is usually a sense of fuzzy, hubristic ideas, and money that would be better spent elsewhere. Anti-ageing research now has a long history, but as far as I can tell, no company working in the field has yet managed to push any therapy to the stage of conclusive clinical trials. In 2012, the Japanese scientist, Shinya Yamanaka, won a Nobel prize for his discovery that bathing single cells in four proteins could rejuvenate them, but using the technique on mice resulted in some developing cancerous tumours.

Besides, even if anti-ageing techniques eventually proved successful, what would be the social and cultural consequences of literally pathologising old age? If we lived much longer, would we also be expected to work indefinitely? How would the planet cope with a hugely increased population, and who would be first in the queue? I think I know some of the answers to the last two questions. They resonate with the negotiations currently going on in Glasgow, and the lifestyles of some of the people gathered there. As my colleague George Monbiot recently pointed out, keeping the average rise in global temperatures to 1.5C demands that each of us is responsible for no more than two tonnes of CO2 a year, whereas the richest 1% of the world’s population are on track to produce an average of more than 70 tonnes a head. Imagine such people jetting around until they were 140, or 200, or even existing forever.

There is something about all this that feels analogous to the space travel efforts of Bezos and Elon Musk, and what those projects seem to say about a relative lack of attention to some urgent issues playing out on the planet that the two men apparently want to escape. In the same way, sizeable investments in attempts to eventually cheat death risk neglecting aspects of ageing that we all face right now. Some of these are about specific illnesses and conditions often linked to getting older. (Bezos, in fairness, has also contributed to dedicated work on cancer and dementia, though I dare say even more help would be welcome.) But there are equally urgent questions centred on people’s everyday lives – and potential answers that could certainly do with more help from self-styled philanthropists.

Notwithstanding the effects of the pandemic, the age-frontier of the planet’s population is already increasing fast. The World Health Organization says that by 2030, 1.4 billion – or one in six – people in the world will be aged 60 or over, and the number of people aged 80 or older is expected to triple between 2020 and 2050, to 426 million. The UK reflects these trends. But as evidenced by this country’s ongoing contortions about social care, we tend to live in a collective state of denial. Consider also the kind of sad facts for which there are so far no biohacks. Half of all people in the UK aged 75 or over live alone – and, according to the charity Age UK, half a million people over the age of 60 usually spend each day in solitude.

Thinking about eternal youth may be a diverting intellectual exercise. But as a matter of scientific fact, we know that strong and stable relationships and immersion in communities result in people living longer and healthier lives, and the loneliness that too often grips people’s later years has the reverse effect. The idea of co-housing, whereby people – often of all ages – are resident in communities built on mutual help and everyday socialising, embodies exactly that realisation. So, at their best, do the kind of modern retirement villages where people live in their own spaces, and have access not just to company, but an array of services and life-enhancing leisure options.

But how do we recreate those innovations for millions of people? And if we did, what would it mean for our health and care systems, leisure services and transport networks? As against the cliche of retirement to the country or coast, would it be good for older people to live nearer the centre of cities and, if so, how would that work? Most importantly, if there currently is a chronic mismatch between our housing stocks and what an ageing population needs, what do we intend to do about it?

Leaving aside huge questions about their personal and corporate tax arrangements, imagine if the most trailblazing, publicity-attracting projects of 21st-century billionaires involved not leaving the planet or living indefinitely, but the kind of earthbound things that could transform lives in the here and now. Just as the Scottish-American businessman Andrew Carnegie used the money he made in the steel industry to fund the building of 2,500 libraries around the world, they could plough their money into co-housing projects, retirement communities, adult education centres and more. Such things wouldn’t be quite as head-turning as the unlikely promise of a world populated by deathless super-humans, but they would be a lot more useful.

Four years ago, scientists at Harvard University published the latest findings of a study of the lives of 268 alumni; it had started in 1938, and was eventually expanded to include people in inner-city Boston. What it said about longevity was striking: not just that “close relationships, more than money or fame, are what keep people happy”, but that those ties “are better predictors of long and happy lives than social class, IQ, or even genes”. Here is what the immortalism of famous capitalists rather neglects: that the most immediate route to living better and longer lies not in hacking our cells, but helping people to be more human.

• John Harris is a Guardian columnist