Many are probably not regretting because the price hasn't started going up X10 or maybe X5 it's current price, but eventually, they should. 

Thanks for listing the probable seasons why my SPS earnings per battle has reduced, I don't think it's my rating, and probably the other two reasons. Even when I've played in champions 3 with a very good rating and some food streak, it varies. However I notice that if I beat a person with better deck or better SPS stake, I significantly earn close to 0.9 or 1 SPS in that battle.