If you sell bitcoins at this stage then of course its an stupid decision to make as price is not too high and if you sell now then you will be getting less profits on your investments so it would be good to hold your bitcoins till the end of the year as price may go much higher by that time and if it goes then selling at that time can be more profitable.
Well to be honestly, selling bitcoin is not a stupid decision. It will be just stupid if you sell it at this moment that the value of bitcoin is at very low price.
Selling is kinda part of our business, we buy, we sell, the different thing is the value you'll loss if you sell it now but if you will hold it until the best time to sell it you'll have big profit from it.
It depends on us on how we will going to deal with it. Facing ups and down is a normal thing in life its just up to you on how you will handle it.