Besides the rise in price is also the corresponding rise in difficulty.  When I started this pool in 2015 you had a pretty decent shot of hitting a block or even two by renting 1PH.  The very first block I found was with a rental like that.  Now, a 1PH rental has a very slim chance of finding a block.  Of course, the difficulty when I started was 65,848,255,179.  A bit different than what it is now