Bitcoin probably is in a bubble and will see a big crash eventually, could keep growing until $20k-$30k before it happens though. It doesn't matter however if it's in a bubble or if its about to crash as history has shown it will go up in the long run either way, the safe bet is to buy and hold. If you wish to cash out some gains now that is also good for financial security but if you don't need that money its usually a safe bet to just hold on to your coins and come back to them in several years time.