Is Twetch a 0 sum game?

It all depends, there is BSV moving around the ecosystem. In theory, if the platform were to reach millions of people then there would be popular Twetchers who would make a career out of Twetching.

For me, so far, it's not. I am losing bsv overall. Not sure if the friction, as in fees, are too high still, or if my content just sucks. Overall this has led me to post and engage less unfortunately.

Don't worry. There aren't that many users yet. Soon enough Twetch will be flourishing.