my gmod folder is 145gb

How many workshop items you subscribe to? It is very intresting my friend of mine had more.

Remove unnecessary addons. The workshop usually specifies the wrong file size

i lost 400gb you know, and i still downloading MORE

Get rid of them, if you don't want your PC to go to the next world!

once my gmod folder was about 564GB (the game no longer worked when all of the addons were enabled at the same time)

Not bad, but I saw heavier gmod

probably just tons and tons of addons over the years

Delete your cache files they are useless files

heh amateur i have 1 tb and my pc is blow up

You should oftenly clean the cache in garrysmod. If you don't it will be very painful to delete them. And try to avoid useless addons.