People bet on sports not just because they're gambling but also because they have fun watching the entire game. If you are not a fan of sports, that definitely won't make you enjoy it. Stress is just coming from being forced to gamble in a game that you don't like. Even if all are gambling, we also have different choices.
This right here is not universally true, because I have seen people who complained about not being able to watch a game that they placed a bet on because to them it’s usually mentally draining watching a team play against another while your money is at stake and if it happens that the team you bet on is struggling against their opponent you’ll feel too much pressure.
I’m not saying that it’s not fun to watch it though but there are times where you’ll be stressed out rather than having fun like one initially intended to do.