It's not a nice thing to think about, but we do have to consider how long we're likely to be on this planet, any dependents, and whether we're happy scrimping and having a miserable existence when we stop working, or if we'd like to be more comfortable. Then we have to plan accordingly.
I mean, if everyone in your family lives to 90, you might prefer to be a bit more frugal now, so when you're retired, you don't have to ration your food and shiver all day. If everyone in your family dies at 60, you might want to take that holiday whilst you can enjoy it and make memories.
It's a bit of an educated gamble (well, really educated if you've had gene testing) but ultimately, it's about finding a balance between how you live now and how you live later, and trying to guess at what later might look like and for how long later might last.
You might put up with something less than ideal in your youth because your body is young, fit and health enough to take it, so skip the luxury to free up more wealth for later. Or you might refuse to put up with it, because you're confident you won't enjoy a long retirement.
If you have kids, you might be relaxed about leaving them nothing. If any of them are seriously disabled, providing for them in your old age and after you're gone might look very different.
There are so many variables and we've all said already in one form or another, it's about individual circumstances. People don't plan what to have in savings or pensions because most humans don't like to think about their life expectancy and plan around that accordingly.