I dont have quitting point or selling point for my bitcoins, I like to have them and I hope I will always have some. I sell when I need money, when I need to buy something, but I have my stash too. When price blow the sky I will still have some, I will sell some, but end game is that I will able to use my bitcoins one day for real, like I will go to and buy some nice car with 0.01 btc? Sounds nice, well maybe one day we will see bitcoin price so high that nice car will cost 0.01 btc and people can buy them directly with bitcoins.