There are a lot of expenses. The fire stuff you read about people retiring after a few million is often heavily biased towards young single people where you can move to Thailand and live well but falls apart with a family.
People don't retire and live in the city after making a million a year for a few years. Maybe they're all stupid, but chances are they aren't and you're severely understimating how much things cost and how much you're taxed.
If you're making a million a year you'll want nice things for your family, that includes space for your kids to enjoy their childhood, vacations together, good food, transportation, and other things, otherwise what the hell is the point of working hard?