I don't particularly disagree with you about gambling, though there are different types of it. Most likely you are talking about dice and Bitcoin casinos with house edge where you are invariably set to lose in the long term. On the other hand, there are a lot of games often referred to as gambling too, but which require both luck and skill, for example, poker. Thereby, investing in these skills may be profitable, especially if you have a predisposition for such games and love playing them. There are also sports betting which can also be considered as gambling. Though betting arbitrage often used in sports betting seems to have more to do with trading than gambling...
That is, it can be loosely called as investing
Poker requires lucky just in short term, after a thousand of hands you will know if you are a good player or not. You just have to be better than the others in the table but it is not easy, it requires a lot of study and you will see few profitable players over there... And you have to pay an rake to the house.
About sportbetting, I don't know how much it's lucky and how much it's skill, in my opnion the house will always win.If you are using betting arbitrage in sports betting, your chances of losing are not very great and usually depend on your ability to quickly find and correctly assess the arbitrage opportunities since this type of arbitrage has a very brief opportunity window of a few minutes only. In this case you win by playing against two houses (called bookmakers) at once whenever there is a discrepancy between the opinions of the bookmakers on the outcome of some sports event. It seems to be the only way of earning profits through gambling consistently and securely...