"I would sell all my Bitcoins if..."
For me the answer is never.
If BTC goes up a lot and makes me very rich, then I will certainly hold on to some part of it. If it falls and goes to 0, I will still hold on to it in the hope that it may recover rather than selling it for little.
No offense, but it seems it just the same as investing in "rocks"
You'll never use them.
im not a geologist but im guessing the earth and the moon are "rocks" too
as are diamonds ,saphires,rubies ,emeralds and most other things that has value
before we went crazy printing paper money