People use to hold bitcoins because the biycoin analyst says that its price will touch 10k $ mark in 2018. And in the current month people has witnessed that its price has jumped from around 4k to 6k. So that was a good jump in crypto market. So peiple beleive in its rise.
they all believe it and it's been proven that many of the bitcoin watchers can still catch more than $ 10k so do not throw away your bitcoin before it reaches the highest price even the highest.. all markets say the bitcoin jump is like a step tiger legs ran within seconds

Highest? When is highest price? No one knows that because it depends your target, the market don't give you the highest price of Bitcoin, it will be create by the demand and target of the traders in the market. So, you can't sell your Bitcoin at highest price if you have not target.