the data is only from a small group and they are investors to begin with so 2% can be a correct value. but it in no way represents  the whole population or the whole world. when you look at a larger scale then it does not even reach 1% and so far the data (which is from 2017) was during one of the bigger bull runs that bitcoin had and lots and lots of pumps, hypes, advertisements of altcoins which attracted investors even for a short time.