If I have lots of bitcoin then I will spend some of them when necessary and rest I will save it for the future as bitcoin has great future ahead which will show us some high price of it so at that time we should not be short off coins and should have enough coins in wallet to enjoy higher profits.
The same thing here, i keep part of my bitcoins and i sell part of it.
It is not good to sell all because there is no possible way to know how much bitcoin will be worth in 5-10 years from now, maybe we are all holding fortune. If I don't need money i would hold them all.
Almost everyone will go with this option. This strategy is perfect if you are really lucky enough to have large number of bitcoins at present when prices are about to touch 5k dollars.
Bitcoins are best when saved for few months because in this way their prices increase very much whereas spending bitcoins is equal to losing opportunity of becoming richer in the near future.