Is Hosting a Garrys Mod Server Even Worth It?

I don't think so.

Starting a DarkRP server is a bit like investing in cryptos : You need a lot of money to begin, and the outcome probably won't be great.

You ABSOLUTELY need good addons to succeed if you want to make money via GMod, and seriously, if you are broke atm just know that you'll need approx 50$ minimum if you want to buy fancy stuff from GModStore. You can also leak those addons but you won't get updates for them.