The effects you are concerned about here do not apply until the system reaches "peak value".
Or a plateau.
if I have $100 of Steem Power, then I must contribute $10 worth of value per year.
Exactly, but this also means that if I can only contribute $10 worth of value per year, I should keep $100 of Steem Power at most and sell the rest. Won't this create downward pressure?
RE: When the market cap of Steem stabilizes, most people will start losing money