>>25851024
You're insane for not selling everything at 35-40k, tax free mind you, and buying back in at literally any lower price.
Cost basis is almost meaningless with something like BTC, where you know that years from now it will be worth big bucks.
You do know (obviously) that it's going down lower than it is now. You've been in long enough to know that. Why wouldn't you increase your stack greatly? Having a 1.8k basis means fuck all if you are only holding 6 coins when you could have 10 or 15 or 20 right when BTC tops 100k.