Ok, I'll use a relative as an example. They live very precariously, which is stressful. It cannot be fun at all.
As such, as soon as a little unexpected money comes their way (e.g. very small inheritance from a relative, christmas money from grandparent, left over money on the odd month's wages) they spend this on complete non-necessities.
But then they are always borrowing from Peter to pay Paul and rely on people stepping in to get them out of trouble for the mundane things.
They would 100% argue that they simply cannot afford to save because their rent has gone up and their car has gone wrong etc.
I think it becomes a vicious cycle of eeking out precarious existence. Then some money goes their way and wanting a treat, because why bother schlepping about if they can't have a small treat, right? And then going back to eeking out difficult existence.
It is frustrating from the outside, especially for us who are fortunate enough not to be in survival mode.
So I think a lot of people COULD save money, who don't. But the money that some people would say is wasted brings a bit of joy and reprieve.
And frankly, I can't really begrude people that. But it is only because others (family or social supports) step in that people carry on with it.