Code without pressure on something of your own likings
If you have passion for coding, but are pushed into boring tickets in your regular work, a hackathon opens up the possibility to code in the way you want to. Together with others, so that you can code and learn faster.
Play with others in code
Together you can learn more than on your own
During a hackathon, you can work together with others on topics that normally don't get enough attention. Even better, by applying techniques like pair programming, mob programming and TDD, you are guaranteed to learn faster than you normally would.