If the price of Bitcoin dropped to $100, I think it would be pretty great for a lot of people. For one thing, it would make me feel like I had made the right choice when I bought some Bitcoin at the beginning of this year.
Also, it would mean that fewer people were mining Bitcoin, which means that we'd have less centralization in the system and more people who could actually use it instead of just speculating on it.
This is all assuming that the price drop was caused by a drop in demand (which is probably what would happen). If there were some other problem with the cryptocurrency itself or its underlying technology, then the price drop might be bad for everyone involved—but I don't think that's what we're talking about here.