How can someone rely his own life on a volatile asset like Bitcoin, which is unpredictable on short run? In order to live from Bitcoin investment, this individual has to count on frequent increasements in BTC price, or daily trading. Daily trading is like trading, and Bitcoin doesn't fluctuate only upside. So what is he going to do once Bitcoin suffers a correction?
Everyone needs a plan b, to diversify funds among different investments, so once one of them stops working, there will be others to supply the needs of the investor. It's a basic guideline of financial market to not put all your eggs on the same basket.
He left his artwork for Bitcoin, because he wants to see clearly the art behind the technology. Op, could be a friend, but from his writing the both are
not too close to some extent and Op may not be sure if his friend has fully abandoned his art business. Even if he did, not all
of his contacts will let him go. It's not just feasible to throw away the source that generated money for investment.