It is not a lot to ask for someone in the top x% of earners to set aside a few months' expenses instead of spending every dollar on housing/food/entertainment/etc.
There are situations where employers do mistreat employees, but failing to guarantee perpetual employment is not one of them.
I got laid off again about 3 years ago. It was nice. I got an immediate offer from someone I had worked with before. I wished I could have taken more time off. I currently have several years of expenses available to me.
It really depends on where you are in your career. Money really is freedom in the US, try not to spend it carelessly.
Many people (myself included!) have a hard time saving against potential outcomes and find it convenient to explain away why I don't (as I spend money on non-necessities).
I was actually more surprised that I somehow didn't get laid off at a previous corporation that had multiple rounds of deep layoffs, especially considering how often I had been laid off in the past.
In fact I found out when the department head put in his notice that I was on the list of one of those layoffs, but so many people quit in the meantime that they didn't need to lay off as many people, so he was able to take me off the list. I stayed there a little too long, through inertia and also I had so many 1 to 1.5 year job "hops" from all those previous layoffs I felt I should stick around a bit longer to show I am able to stick with a company when they let me.
It would have been a blessing if they had laid me off, though, it would have forced me to find a much better job much earlier.
Few do, however.
Not always. When I was laid off I wasn't surprised in the slightest. There had already been layoffs and the company eventually effectively shut down.