Going off of my own personal experience, I can honestly say that a 40% gain wouldn't cause me to bat an eye considering I was seeing 5-10x gains easy in the previous bull run on almost every coin...but then again, I let my greed get the better of me back then and totally missed out on making some crazy good money. With that in mind, I would certainly be more tempted to consider selling a portion of my holdings if I can 2x on some of them but I'd still likely hold on to the majority because I believe 5-10x gains are again going to be a possibility in the next bull run that is fast approaching.