I'd say you can have substantial freedom (not luxury) with less.

But 7% yield is a bit optimistic, because you pay tax on nominal growth. Say, if you achieve 8% nominal growth, have a 37.5% tax rate, you're left with 5%. Now deduct 2% inflation, and you can only take out 3% per year.

Thus, your $10m only give you $300k a year (after tax, real), which is enough for 5, I'd say (maybe not in NY, but in many other nice places). However, that assumes 8% nominal return, which is not something I'd bet my retirement on, given current elevated asset values.