Well I think its mostly the bad name the bitcoin itself has because of the criminals that are using it, but that should be no risk.
The other thing I'm thinking is that people are to scared to invest in it because its still a risk you are taking.
People should not stay away from bitcoin just because it is used by criminals as it is not the only currency used by them so if people can use other currencies used by criminals then why not this?
But yes, maybe people are scared to invest in it because they think it can be risky because of the price ups and downs, but they will surely start using it when they will see a grow in price and they will also regret not buying before.