Bitcoin does not support gambling, drugs, or tax evasion. That is a complete myth. I ran some numbers, and drugs and gambling combine for approximately 10% of the network. That's about as much as it is for regular fiat.
The people on Bitcointalk have an irrational fear of government, believing it to be more than what it is—an association of people help organize society. Yes, it is power-hungry; and yes, it makes mistakes—but there is zero reason to believe it will attack a currency that benefits its own people.
Obviously bitcoin doesn't support anything, it's a protocol. But its lack of regulation, allows it to facilitate a lot of things people frown upon. Prescriptions make the price of obtaining legal drugs more expensive, but the public interest still supports it because a few may abuse it. The price of healthcare is even a huge issue, yet the idea of making all drugs over the counter is never discussed. The same people that follow that logic will use it campaign against bitcoin. Despite all the good bitcoin can do, the fact that it can't be controlled is something people fear.