If he has an edge (if) that allows him to sustainably gain purchasing power over time, then I don't see why he shouldn't trade. Buy and hold is risky too because you expose yourself to 100%. Successful trading will decrease your risk even though it's hard to outperform buy and hold for Bitcoin for profit, but this profit comes at a cost.
Most here haven't experienced the 2011 bear market where price went from 32 to 2. Risk management has its uses.
I believe the only one with an edge is the exchange. But if someone can actually have an edge then it's just like playing poker and can be profitable.