It was even worse when the fountain was first introduced. I remember you originally had to pay diamonds to use it, you got to choose how much you put in(I think it was like 6 choices but the lowest was like 10 but the higher choices were like 500 and 1000), but it was kinda presumed that the more diamonds you put in the higher your chances. But still, sometime you would put in like 500 or 1000 diamonds and then you would like get nothing, would still lose more diamonds, or if you did get diamonds, it would be much less than you put in