It seems to me that its entirely possible to combine the fun of gambling with earning money. if you are a professional sports bettor you can enjoy both the thrill and the income it brings. As for slots you can also play them for money but it's important to approach this responsibly. Don't quit your main job right away! 
Jokes aside. it's true that we all love money but anything that clouds a clear mind is not a winning strategy.
You're right that there's a possibility of combining both the thrill aspect and the earning aspect, but this isn't as easy as it sounds, it'll require a great deal of discipline and self control, because it'll take one to approach gambling responsibly and with a completely clear mind.
For example, those who are considered to be professional gamblers can actually do that combination because they're believed to be a lot more in control of their emotions when gambling, so they can enjoy the game while making good money from the activity.
The same way playing on the slot machines could be quite enjoyable too, but the secret to not getting caught up in the whole thing and losing control is by setting and sticking to your gambling limits, have a good bankroll management and whatever you do, never chase your losses.