Colombo,
You haven't mentioned and no one has brought up yet the most obvious, basic questions in my mind (and I've been through a not-unlike experience, albeit not entirely voluntarily). Such as:
1. What are your personal risk profile and personality like? How risk-loving, entrepreneurial, self-driven, etc. are you? You either have it in your blood or you don't... Can you be brutally honest with yourself, most of the time? What rational thoughts and not-so-rational emotions come to your mind when you visualize each of the two alternatives in your mind's eye?
2. How many days / weeks / months / years of living expenses have you accumulated? Do you have a wife (working or not?) / dependents / other obligations? Does the concept of "infinite wealth" mean anything to you? In case it doesn't, go ahead and look it up.
3. The fact that you've got a high net worth client lined up already is a major plus... However, if you and this client-to-be of yours have become "close" friends, as you say, have you had straight-up conversations with him regarding exactly what "do[ing] this on a full time basis for him" implies and what the possible scenarios might be?
4. And yes, it might help
to have an edge, too, that you have confidence in. If you have to ask, that's generally not a good sign...
These are just some of the key questions you'll want to get a good handle on -- now, while you have little or no pressure.
Also think about this: we might sometimes regret the things we do, but we sure as hell regret more, much more, the things we
don't do. Don't let the logical, well-meaning, risk-averse strangers cause you regrets.
