mateysmum, not to pick on you, as others have expressed this confusion too, but nobody is saying that any particular indvidual has or had an individual responsibility not to benefit from what was on offer during their life, in order to donate to future generations (as if that were possible by individuals choosing not to benefit).
What is important to note is that age groups, as a class, operate within different economic environments, and I think there is justifiable frustration in younger people that older people do not recognise this, and seem to think that they - the younger people as individuals - can solve all their problems through hard work, as individuals.
Various different govts have worked very hard not to deny certain age groups anything, on the basis that you will cause an electoral uproar by seeming to take things away (house price crash for instance) but you can apparently deny anything you like to those who have never had it (impossible to buy a house if you missed the boat due to age)
So as individuals, Mr X at the age of 60 living in a £500k house is not personally to blame for the fact that Mr Y at 30 cannot hope to buy one for £300k, which is the cheapest you can get nearish where Y works. But Mr X has benefited from policies that have disadvantaged Mr Y, deliberately, and it is very uncomfortable for him to acknowledge this, as opposed to patting himself on the back for all his hard work over the years, but there it is. It's a fact.