I think the fun in gambling is putting a certain amount of cash and getting the amount in certain multiple rate, gambling is fun when you win either in real casino or online. The part where you lose is usually the bitter experience , most especially if the stake is high.
If people play for fun then it is fine but the moment they want to just make money from gambling either on site or casinos is the destruction which could happen and can destroy them self and the relations ship with others as they will need money to keep playing.
No one is even saying they should not play for fun, but if we really want to be realistic with ourselves, just like the OP said, there is actually not much of a fun when it comes to online gambling and apparently, most people at some point will find out they are simply playing because of the money.
Of course, we may have some exceptions, but it would be rare. This is something we sure know can easily be seen as fun at least for those who are in a real casino.
Of course winning money in gambling is real fun and the purpose of gambling is this that you win some money and when you do this you will feel enjoyment and will be happy till the next lose.
Some people are looking for fun in online gambling but I think online gambling still has no fun and only the easy way for gambling. Online gambling is just a facility and not fun.