There are loads of hungry traders out there, ready to trade in Steem Dollars.

That has not been proven yet.

coupled with an increase in demand

Doubtful.

So the short answer to your question is; the money comes from people trading Steem on the exchanges

Good to know you're aware of this. Money comes from the ones who bought in. Then some of them become voters. But you think they brought / provided little if not no value?