the truth is there actually right many people use bitcoins for illegal items drugs gyns and worse but isnt that true with things like USD to??? so while theres always a few there are many more legit use's for BTC
the truth is that one cannot buy something illegally. Only stealing is illegal. It is the evil government that declares things as illegal. How can you own xyz illegally, if you have paid for it with your own money?!?
Unless you're buying organs or a slave.