The effect of president Trump is notore than what we have seen so far in the last decline in the market value of Bitcoin and crypto currency market in general.
Well maybe that's one of reason why bitcoin price decreased to $10.9 k now after it was $13k (before the tweet from Trump which againts with crypto), but we all know there were some people or even instutional who said they aren't believe with bitcoin, after bitcoin was down to $4k months ago, they are buying/launched their own coin (e.g Jpmorgan)