The argument against this is that founding a startup, when factoring in the incredibly low success rate, may not be the best strategy to gain money. Joining an early stage startup (with equity) that's clearly on a growth path, or even working for a Google, Facebook, etc. is a much better bet for making money.

Also, startups, where startup means creating a new unproven solution intended to achieve exponential growth, are unfathomably hard. It's hard (in my experience) to stay motivated in the face of startup hardships when one's primary objective is money.