I really dont understand why people think this is somehow dramatic for bitcoin. Let it go back to $1 or $0.1, so what? it doesnt matter (unless you happen to hold BTCs you bought at $15 thinking youd get rich). $0.1 is as much a speculative value as $10 or $100. At this point, none of them are "correct", and all that really matters is if it gets used more widely, and that is not dependent on its value.
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.