To answer your question I will have to ask you another question. How many people do you think bought bitcoins since it crossed 1000$ mark ? If you bought some BTC at 1000$ what will be reaction when you see it at 10$. One you would feel sad that your investment is not rewarding you as much as it should, second thing that would cross your mind is "this thing did rise to 10000$ in the past so what if I buy as much as I can and forget about it for the coming 5 years." the hidden gambler in you will take control and you will buy as much as you can.
This second thought would be common in all BTC holders. If it comes down to say 10$ people are going to buy it like crazy and when they do, the price will bounce back to something much more higher in the coming years.
A large number of investors today are institutional investors or simply people who are too rich. For eg The Winklevoss Twins who hold more than 11 Million $ in bitcoins which they bought in at 120$. If BTC comes down to 10$ what do you think they will do ?
I get your way of thinking in fact I would do the something with the crypto-currency that I am HODLing. After all I have not spend money on it (except for electricity fees) and I have witnessed its potential worst state. The only reason in my opinion that would lead to people leaving bitcoin would be that they are moving to something else that can massively increase their profit, with the belief that bitcoin can no longer benefit them as it did. And that can happen in the far away future however it is unlikely to happen anytime soon