"Mark Cuban has attacked Bitcoin on Twitter, claiming it is not a currency, it is a bubble, and that the whole system of valuation concerning it is wrong. But is he right?"
https://futurism.com/mark-cuban-asserts-that-bitcoin-is-not-currency/His comment caused the Bitcoin price to drop before it hit $3000. He said Bitcoin's increasing price now is a bubble. What do you think?
What makes you think it is his comment specifically that caused bitcoins price to drop because a lot of popular people have repeated this line many times without it having an effect on the price. Perhaps it was just a coincidence.