Long story short, I'm living a life very similar to MMM in terms of nature and amount of work (not much, and I choose it). I just don't have the massive cash pile yet. I'm self-employed and work in an industry where the rates are very good but the work is quite hard to come by; you basically can't get 40 hours a week unless you work 6-7 days a week. That business is, believe it or not, is guitar lessons (being self employed is basically a 100% pay increase over working at a store; my hourly rate is quite high). Its been quite steady income compared to my other freelancing friends; its just very difficult to get students before 5 o'clock.
I made the conscious decision to avoid working 6-7 days a week because I didn't want to become a workaholic. Working 6 nights a week (or even just 5) and Saturday ain't so great for relationships or family. Of course, this means my income is lower, but happiness is higher.
I live incredibly inexpensively (about 1k a month on non-business expenses) and save a substantial portion of my "take-home earnings", which I calculate as gross minus taxes minus business expenses. A world in which I retire before 50 with substantially greater than 100% of my current earnings from 100% passive investments is entirely realistic (I'm just shy of 32 and only got my financial act 100% together last year. I was quite good at paying off student load debt, but not as great at saving money).
Here is the catch; I would be very pleasantly surprised if I ever made enough to max out both my Roth and SEP tax-benefited investment accounts. This means that all of my massive savings will be locked into tax-advantaged accounts for at least another decade after I can retire.
Assuming I'd want to stop working as soon as my account reaches self-sustainability, what is your advice in this situation? Should I invest in non-tax advantaged accounts? This seems very counter-intuitive to me. (note that this isn't a given; I may decide to work 3 days a week, take 2 months off during the summer and 2 weeks of at Christmas, and let my cash-pile continue to grow).