What happened to the price of Monero? Why did it plummet so?
IMO this is classic pump & dump, because the whole XMR system looks like a financial bubble to me.
Certainly XMR was pumped at times, and dumped at other times (right now, for example). This means that at certain times XMR might have been overvalued, and probably undervalued right now. So, if you believe in XMR, it might be a good time to buy now.
Disclaimer: I do :-) Because if a quality coin is dumped after a pump, it's different from a non-innovative sh**-coin, for which the pump&dump often is the beginning of the end. For a quality coin with a good dev team, a dump is rather a good opportunity to enter the game. If you believe in the project, that is - you have to make up your own mind on that, but there's plenty of material and links in this thread which you can study and convince yourself.