College is proven way to improve productivity and lifetime earnings. And it's scaled fairly well. And unlike poker, it's not zero-sum. "In fact, apart from very specific cases, I think that school is a bad thing, not worth doing even if it was free." Very wrong. You're not going to become a doctor, lawyer, nurse, accountant, etc. by playing poker and traveling. You're not going to get recruited by an employer because…
To your point, you also aren't going to become a zookeeper or programmer by playing poker or travelling, but you also won't necessarily become one by going to college. You WILL become one if you make the effort to do so, it doesn't matter whether it's in college or elsewhere.