Actually you have a point, but on the other aspect, I can say that one among 10 strategies might work. Although winning is by luck and it's like luck and time works together. When you are using a particular strategy on sport bet always, one (1) day you can win with that same strategy because not everyday the teams you played will continue to play the opposite. (eg) Like betting on Manchester United to win Manchester City and it has been cutting (ending the other way round) one day Manchester United you played to win will win. So am only trying to say, strategy, luck and time have to work together for a gambler to win.
It turns out that the situation will simply play the opposite way, although in fact we should not win. It turns out that only luck will happen, and probably strategy has nothing to do with it. Strategy implies that it will systematically work always or at least over a long period of time. Generally speaking, I think that only a very small number of players have really come close to a real strategy that will allow them to win over the long distance until a downswing occurs. However, these players will never share their winning strategies with anyone, I am sure of this for sure, because the more players know about it, the less effective it will be.
Sometimes luck can be much more powerful than strategy, or what I mean is that the success rate with luck is much higher than strategy, we can see that often our strategy goes wrong even though we have previously analyzed a team very well and in general it is true that the team is much stronger than the opposing team but in the end they lose, and also sometimes there are always some gamblers who bet by choosing a weaker team because they do not have any knowledge but in the end they win, that's the extraordinary luck but unfortunately luck is something that can never be controlled.
On the other hand, actually strategy cannot be used as a weapon to achieve victory, in my opinion in the end gambling is still gambling that has risks and can never be fully predicted in any way, because you will never know what will happen in the future. The last one, yes, I quite agree with what you said that if there is a strategy that is really effective to always be able to achieve victory, then surely no one will share it with others.