Because on Crazypool I'm getting about 10% more in profits, compared to the pools you mentioned.
Crazyypool: 1.64 TH
Total network: 727 TH
Crazypool has only 0.22% of the total ethereum network hashrate. If it's 10% more profitable than other pools, why don't everybody switch?
nanopool.org, 2miners.com and miningpoolhub.com has 90THASH (12.3% of the network)
I don't see thing on proportion:
Nanopool has 37.89 TH/s with 47829 miners
2miners has 26,33 TH/s with 56957 miners
Miningpoolhub has 17,85 TH/s with 140284 miners
Crazypool has 1,65 TH/s with 2869 miners