The main feature of crypto currencies is their anonymity. I don't think this is a good thing. The Governments ability to find money laundering and tax evasion and terrorist funding is a good thing. Right now crypto currencies are used for buying fentanyl and other drugs so it is a rare technology that has caused deaths in a fairly direct way. I think the speculative wave around ICOs and crypto currencies is super risky for those who go long.
I dont think why billgates say this one, maybe he dont want to make their friend relatives and other people to lose their money in bitcoin because the price go down and go up rapidly. I agree to him because it is risky