"Safe withdrawal rate" is usually pegged at 3.5% to 4%. On an initial lump sum of $1MM, that's $35K-40K/yr, not $12K per year. (I'm not sure where the 7% came from in your post.)

Good scenario modeling tool: cFIREsim: http://www.cfiresim.com/#

You can login as HNHN : HNHNHN and look at the scenario I modeled using the information in this thread. That has a 100% success rate from now until 2080, assuming a 3.5% annual spend ($35K to start) AND ignoring any new money being added (from his mathematics or other work).

It's not Maserati money perhaps, but it's absolutely a secure retirement for someone currently living on $25K/yr.