Along with the premium version, they have a crypto currency (TON) that can be used to buy things on the platform from other users, and I think you can also buy things with real money and they keep a small commission. Also there are some small ads in very large channels (not groups, channels only) and ways to gift “stars” to other people, like Patreon or sth
While I love traditional forum structure, I don’t think it would be great to transition later from one structure to another completely different. In my mind, the only thing that needs a bit of tuning is the “Hot” algorithm of the front page