Biographies of famous scientists edit out their mistakes, so we underestimate the degree of risk they were willing to take. The choices that worked become conventional wisdom and stop looking like bets at all.

Newton made three bets — physics, alchemy, and theology. One of them worked. But they were all risky.

In Newton's day, physics, alchemy, and theology seemed roughly equally promising. No one yet knew what the payoff for inventing physics would be — if they had, more people would have been working on it.

Alchemy and theology were, in Newton's time, what Marc Andreessen would call 'huge, if true.' Hindsight makes them look like obvious wastes of time; at the time they were live bets on enormous payoffs.