Well, if I make 300% APR with a token, I really do not care if the profit comes from price raise or having minted a bunch of tokens that kept their individual value. I mean, they can even go down in price if I mine a real truckload of them.
300% APR usually does not happen over a year. Sometimes it does. Other times, it bursts spectacularly. Splinterlands are most likely going to have what dCity has experienced - a correction, a bunch of buy-high-sell-low people badmouthing it and a couple of smart grinders with full pockets. Or maybe something else.
People in the system can set the token value (by printing or burning) but not the value of the system - that is decided by the people outside who either join or don't. Unless the value of the system rises, there have to be losers as well.