Not quite. Appropriate bet sizing is related to volatility, but that doesn't make it the same. This is what I meant by imprecise definitions. Sure, two small be

Not quite. Appropriate bet sizing is related to volatility, but that doesn't make it the same. This is what I meant by imprecise definitions. Sure, two small bets are technically less volatile than one. I think this is a tricky road to walk. Whether its a diy version of modern portfolio theory, or a day trader's take on martingale system... EV doesn't matter if you're not trying getting market returns. If you very investment is a speculation, a risk. IDK what you mean specifically by "professional gambler," but most pro poker players are staked by others. That basically makes a martingale strategy viable... not unlike a "two and twenty" wall street trading firm. "Professional" in both gambling and finance are positions, not skillsets. A professional investor invests other people's money. Same with pro gamblers, generally