With the cost of living, 250,000 would last 2-3 years, is all. Ok, depending on what you are used to living on now, I suppose.
You could buy a house and new car outright, for around, or under, 125,000. That leaves 125,000 to cover bills and taxes, so, really, you're looking at more like a year and a half, or two years.
Now, if you rent instead of buying, you will have the money in bulk longer, but you'll wind up paying more.
So, 250k IS a nice number. It's a comfort level number, I think. For us, a family of 5, it would mean that we could buy or build a house, pay off student loans, and get a new car or two, and still have a tiny bit left over to start a savings. But, in no way would it be the kind of money that would allow us the comfort of leaving our jobs forever. Maybe for a week or two to fly to Cancun, though.