Without being too flippant, if you're 75 and imagine yourself having somewhere between 0 and 20 years left - 2 years is a long time.
Some of them can cope with the isolation (and there has been a lot of isolation for people living alone or even in a couple who stuck to the rules). Some have, to all practical purposes, become housebound through fear now. But others decided after they'd been vaccinated that they'd given it their best shot
and they wanted to start going out, visiting family and friends - and take their chances.
Unfortunately right now, with Omicron looking like it's good at infecting people (including those with some immunity through vaccine or past infection) the chances are that if we're all "taking our chances" the hospitals will be filling up fast.