Funny question because let's say I tell you that it's 100. Will you believe me? Will you feel confident in your skill when after 100 bets in dice or slots you are in profit? Will you tell everyone that you're a good player after that?
If I tell you that it's a million bets, will you play long enough to try it?
This thread cannot answer your question and even if it does, you probably won't do anything with that knowledge.
Don't know about you, but I find the question serious, and I think he isn't asking about us but he is more concerned about his performance. Also, he is talking about sports betting here, and not casino games. All of us are equal in casino games although our luck can come randomly, e.g. I am lucky today and can win while you aren't but the next day or so, you are the ones who are lucky and I am the opposite of it. Luck can still play a role even in sports betting, this is why he said someone can get those percent after a certain number of bets. To know our true skill, it is better to place more bets, as the winning percentage can still fluctuate.