BTC price will be around 800 - 1200 USD this year, high price means that BTC mining is more profitable. So it is also the right time to sale some spare BTC.
What is "spare BTC"? I think there is no such thing. All the fractions of BTC we have are not spare for us. We love then and we cherish them.

No one wants to sell them unless we are in a desperate need of fiat money.
well loving the price right now and keep waiting for more, you are correct to hold more and not to sell it expect even more higher value
in coming days and if you are in need just sell some but not everything unless you are just doing day trade and you are just aiming for
little profits from day after day,.