nishi, I see these stories a lot and it makes me laugh that people are so f***ing careless with their property. It's like they lost all common sense once they got the system. Honestly, if you have a brain, and you use it, and you take precautions, this shouldn't be happening.
You don't have to swing your hands like a weirdo to play any of the games. And if you do, just hold onto the damn controller like you should
be doing. Even if you have a sweaty hand at the time (which you should...I dunno...wipe?), holding onto the thing should not be a problem at all. The strap is there for extra support, not total prevention, you still need to actually hold
the controller regardless. If you're swinging it with so much unnecessary force that you break the strap and fling it into the TV, then I don't think the problem lies with Nintendo's strap...
My mom plays boxing and bowling all the time and she puts in more effort than she needs to (she actually does the walk up and the hard swing for bowling) but she reads the warnings before each game and knows how to grip a controller so this is not even a problem. Our strap is still just fine after daily usage. Those strings are a lot more durable than they look. The only way she'd break the TV is by just plain letting go of the controller and not using the strap at all.