The expected return of a year is not independent of the year before. Rudimentary models that many financial advisors use don't account for that. Even the more sophisticated folks don't account for it enough as I think is appropriate. They think they've observed dozens of years and the evidence says it's nearly impossible for the market to go down (as a whole) over a ten-year period. I think they've observed only a handful of decades and therefore should have very low certainty.

I'm still heavily invested in the stock market. I just think you should be very cautious in your assumption of how much money you need to live comfortably on interest/dividends in perpetuity.