The cost of "hosting" is less than the cost of "running".
In terms of storage space, there are times when you have to upgrade. Take the torrent file of custom themes on the archive site. It is ~50GB. This implies that Erman must have been paying enough for at least 50GB of storage, plus whatever the splashes/badges/website took up (probably not that much).
Then you have to pay the staff/developers of the site (usually). I doubt you will get away with creating a secure, reliable user system for free, even if you don't create it yourself, you have to buy it from somewhere.
Then, you must consider the time it takes. "Time is money" and too much time without any results causes a lot of discouragement.