Playing a ball centered sport such as Soccer or Basketball is practically free outside of buying a ball and getting shoes.
>I read and write but I mostly shitpost or doomscroll on the internet.
Depending on how you shitpost and doomscroll, why not try coming up with intricate internet-based writings, for example think creepypastas but steps above. You can also try coming up with a fictional world. You don't have to write a book or anything, but you can lay multiple foundations and worldbuilding.
You can try getting into art. >PS/Paint/Drawing/Etc
Is free with apps like Gimp but if you want stuff like Adobe it's incredible easy to crack/torrent. This can even be combined with your writing or reading. Concept art for readings you like or writings you come up with>Music
Like music? Try making some. Multiple DAWs are once again, easily torrented/cracked. You can also get VSTs/Plugins for free as well.