We may not able to determine because there may be no certain or specific research about these. Moreover, many people that are involved in cryptos are also anonymous and they don't tell each other about their investment. And bout success, what kind of success are they? Everybody's success may be different from others. So, what kind of success definition it is?
I personally don't pay attention to how the percentage of people succeed o crypto, but how many more people, institutions, and companies are involved and entering the crypto.