I love them, even the internal ones. If you don't enjoy them or find them to simply be 'work', they're probably not meant for you. To me, they're a party. The fatigue and focus bring out the kind of vibes you'd get from late nights and alcohol. The focus on a topic means you have an icebreaker. There's low stress socialising like lunch, and there's high stress socialising like go karts and hackathons.

The goal of hackathons is to fail, but fail hard enough to have a spectacular demo. You're not building anything to last. You're experimenting with a new stack. You're building a feature that wasn't there. Whatever you end up with, you have to throw it away, so you're not attached to the code and go deeper than you otherwise would. This failure gives you data that you otherwise would not have.