you think this is the right time to buy and hold bitcoins? because from 19k its 11k today. 
No one knows the honest answer. But sure. Buy in.
It has the potential to go up. Nut it also has just as much potential to go down.
Also look into some ALTcoins.
Bitcoin does have the highest potential to grow its value and also has the highest dumping price in the market when its down time. Consumers should invest on every coin depending on their capital because not everyone is capable to invest more bitcoins since the value is very expensive, sometimes we can also rely on altcoins since there are also alts that are profitable for long term holding.