It is up to us to improve Bitcoin and get rid from fraudulent and illegal activities involving Bitcoin. We should not support fraudulent and illegal activities, we should not protect criminals or scammers. Bitcoin is very useful but if some criminals will use Bitcoin to purchase a weapon, where possibly people are murdered from, Bitcoin will take damage and we should not support it.
Bitcoin is more popular as an investment asset that provides great benefits in the long term. I would not think too far to use Bitcoin to buy illegal goods. Even if people in illegal trading syndicates use Bitcoin as a means of payment, it means they are really using Bitcoin as it should be. I do not justify the transaction of illegal goods, but more on the use of Bitcoin. In fact, there are cases that have been revealed, so they can be tracked.
We can control how we use Bitcoin to transact, but we will not be able to control other people with the Bitcoin they have.