Very nice analysis! One thing I would argue was 401K

Given the stock market for the past 20 years, it's hard to achieve your estimate even if people max the pre-tax saving.  To get to your high-end 401K result, s/he has to be a very good stock market investor -- that is not an average person, though it might be common in this forum.  All in all, your have raised "average" bar too high.