Even $15 is quite low is Bitcoin really catches on. You don't lose until you sell. Expect the value to double each year which means that we're back at $15 in 3 to 4 years. Sell then if you feel like chicken out. If you bought at 15 and chicken out now it's almost total loss. What's the big difference between total loss and almost total loss. No point selling now.
A bit late now, but people who sold at $4 could have bought back in today and cut that 3-4 year wait down to 1-2 years. That's the thing, this dog CAN be traded on the way down. It's just bagholding that is a terrible strategy in a bear market. And people selling today at $3 might yet have an opportunity to get back in at $1.25.
That's all OK if you're sitting in front of the screen all the time. But Bitcoin is traded 24/7. What if I sell my Bitcoin, go to bed and then some stupid online book store in the US makes an announcement that they'll accept Bitcoin? Buy it back at $200? I think I'd have to iron my fingers like Dobby the house elf the next morning.