That 1.5M isn't inflation adjusted. If there is 0 inflation between now and when you die 1.5M is plenty. However the more inflation there is between now and when you die the more money you will need, the later you need to retire, or the less spending money you have. (of course we need to asking how things like social security fits into your plans as well, but this is already complex enough).

If you 22 and used to a FAANG income even with saving $25k/year every year you need more than 3M to retire retire without losing quality of life (even though most of that is luxury).

Are you willing to live on less, or will you discover with your free time you want to spend more money (hobby supplies? Now you have time to travel - maybe first class). I can't answer this question for you, but you need to think about it. Worse, your answer is likely to change over time.