Because I think Bitcoin is still way too complicated for average joe and thats why 99% (or a bit less)of the world still dont have a fucking clue about Bitcoin. You could see when the scammer Jordan Belfort (Wolf of Wallstreet) just said "I would never buy bitcoin because it would be so easy to just steal them from my phone" ..... Obviously he didnt get it, and doesnt know nobody can get his bitcoin if its sent to an address that only he got the key of, stored away safely. So even this huge finance guru hasnt got a clue how bitcoin works. Now for the most part of the population its even worse. So I am thinking it needs some huge new products/killer-uses for bitcoin to explode faster.
If you look at the history of bitcoin,the people who started using bitcoin in the beginning were people who understood technology and it is true that it is really difficult for the average joe even now to understand bitcoin fully ,all they know is that it could help in double your profit in a short time but do not have any idea on where to begin,these are the problems i encountered when i started taking classes regarding bitcoin in a meet up.
So the 2nd part of the question, lets say there was a new drug that helped everyone live cancer free, disease free, add 20 more years to their lives on average. But the governments would ban this drug for some reason. So it would only be available on the darknet... for Bitcoin... And governments would kind of tolerate this... and the media would be all over it.... Explaining how to buy it....... How much do you think would this mean for bitcoin? Could the market cap double, triple, 50x?
Bitcoin is not the safest way to purchase goods in the darknet,
there are other coins for that use,so bitcoin wont be used because of its lack of anonymity.