Part of it is because I don’t believe in the 4% rule, I think it’s way too optimistic moving forward.
My assumption is just that my investments will keep up with inflation (0% real return). So, if I live til 100 (unlikely, considering family history I’ll drop dead at around 75 at best) the money I have will need to last me 65 years. That’s about 1.5% withdrawal rate. $4M gives me $60k a year inflation adjusted, which is what I am comfortable with. When you look at it using this math, you can see how $3M is not an obvious retirement number. It could be for some, I’m sure.
Another part is being surrounded by very successful Silicon Valley people: a lot of my friends have net worths around the $10M, so there is a bit of FOMO as well.
Also, I really don’t have a lot of productive personal projects, nor desire to spend my free time programming, I don’t like programming. I envision my retirement volunteering, reading tons of books, enjoying time with my partner and family, and eating street food in SE Asia.
Lastly, while my family is a modest middle class one, I grew up with extremely limited means: I never lacked food or shelter, but my parents never spent any discretionary money on their kids, so I always felt incredibly poor compared to my peer in school and college, who had toys, clothes, fun money for activities. Had to work on my own for even the smallest purchase, to the point where I would have to think very long and hard in my teens to buy a $1 snack. That had profound effects on me, still to this day.