I got into the bitcoin again last year after losing all my 4.5 bitcoins to ponzi schemes early last year. I bought in bitcoin again at $20k. Now bitcoin is $6k+. I'm regretting my actions. 
You should already know if the price moves up so fast that the supply of the item will decrease and cause the price to go down again for the next period, if you think a price will continue to rise even though it has exceeded 100% profit then in my opinion it is a truly wrong action