Their is 2 types of answers , gambling is wrong and gambling is not wrong,
gambling is wrong, if you play in casinos and play without strategy you lose you money , but what ever happens at the end the site owner wins and you are going to lose it .
gambling is not wrong, if you play in sports betting and that too like business, in business we sell products at 5 or 10% margin itself , so in sports betting it will earn you only 10 or 20% but at the end you will see that you are in profit .
So you mean that when you are in sport gambling you will end up in profit but others will just lose? I guess you are wrong on this, every gambling need luck to win no matter what type of gambling it is but different from sport gambling, it is based on gathering more information to win so these are two different kind of things