Not so. Renaissance people (there are a few, even today) tend to end up underemployed. If you want to be a "business multimillionaire", you go the opposite way. You focus, you narrow yourself, but you have to focus on something that can actually make you money (i.e. not medieval history).

Why are most of the true Renaissance people underemployed, obscure, and financially mediocre? It's because the only thing that can tell a polymath from a dabbler is time.