Combination bets have their uses. The biggest challenge is that all the included events need to be successful to generate a significant profit. In practice, however, most people use this type of bet more for fun, combining several unlikely events. And that's precisely what makes it even more interesting: the excitement it provides.
The fun is there and they don't mind losing even for once and so they can still do that next time if they fail. But if someone who's serious with their bets in parlays, they won't just do it for fun. They have an aim and that's to make some money out of it and even so, there's a reason why they're doing that. The potential of money in parlays are greater but of course, we know that the risk is higher than the usual. Once it's already started, it can't be helped to stop doing it repeatedly because as you've said, it's true that the excitement that it gives is unmeasured.