What's a "hot take"?

I agree with the answer above. You need to pour a fair bit of effort into getting on an Olympiad team. Whether you get a PhD is more a question of economics, IMO. If you're showing that much promise there will be many other temptations, and bear in mind it's not just rich countries that have math kids, there's plenty of olympiad kids who need to get out and make money when they've done their degrees.

The kind of work you do in a PhD is also quite different. A math contest is a few questions with definite answers and a time limit.