Thanks for the info.
That is useful to get a rough idea of things, but let me just note a couple things.
1. It uses a 10% return assumption and a 0.2% investment expense ratio. Besides quacks on cnbc I'm not sure who else would predict this sort of return going from the current market valuations. If you're using 0.2% as your expense ratio the only funds that would fit this are mostly us index funds -- it's been quite a while since sophisticated investment types have recommended anything like a portfolio 100% in an s&p index and/or expected 10% from such a portfolio.
2. This being said, the projections can change wildly if you adjust the return down to a more reasonable level of 7%, or 5%. This would add years to the time until you get to retirement and require a much higher nest egg to allow for 100% safe withdrawal.
3. The study reports that there's little difference to retirement between someone making $30,000 and sombody making $100,000 or $200,000. Well, this goes without saying if the $100,000 earner continues to spend a similar percent of his/her salary as the $30,000 earner. But LBYM is usually an integral part of retiring early and the big earner can quite easily save a MUCH higher percentage of his/her salary. The methodological mistake here is clear.