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.