Don't you love making and playing games? Did you ever try to make a game? It wasn't easy right :/ So why not spend next two weeks learning, sharing tools and/or resources which everyone could use in their game development process?
If you love art you can create texture packs which others could use, if you are into music make sound effects and music. If you are into coding share your cool homemade engines or share tips on making programming easier.
Do you remember how you started making games? Do you wish you had some resource which doesn't exist yet? Then make it so those who are starting out would have a head start (also you are likely to learn something even from restating what you already know = > win win win situation)! If you have some cool tips or always thought that you could make an awesome tutorial on some game dev related topic then its time to act!
Finally you can submit games so they could serve as inspiration to others and show that it is indeed possible (original and preferably new content only). You can also as for feedback on them or provide source code as a learning resource for everyone!
So how do you win at the end of the day? Whats the reward? If you actively participated in the jam you probably learned something new. Also you now have this awesome collection of resources available to you. You got a chance to make new friends in the community tab and maybe even found a buddy or teammate to develop games with! At the end of the day having made a game or learning a new skill is an enormous step at becoming better at game dev!