I was about to say it's the million dollar question that everyone wants to know but doesn't know at the same time - and then yes, I saw a poll!
I think it's something that each individual has to think for themselves, and I went through this process as well. But complicated maths aside, I picked 1 million USD because I think it's more than sufficient for me. At 4-5% return a year, that's 40-50k USD of interest/passive income annually.
The amount depends so much on location. And while it seems like an easy decision to move somewhere more affordable, that comes with its own costs. If I had grandkids, would I want to live far away from them?
Yeah I think it's also the lifestyle we want... Of course, the trade off is having to work longer.