So, if I weren't sure that cryptocurrency was in a bubble before, I think it's safe to say that when DogeCoin pops a $2B market cap something big is happening. And that big thing is probably not good.
Anyway... more importantly, there's absolutely no way anyone is able to cash out anywhere close to $2b in dogecoin haha.
I think what people don't fully get is that these small coins had 0.1% the market cap of bitcoin over the past few months, and it had just <$100k volume per day worldwide for most of last year. (about half of a single walmart's daily sales). That means it's pretty easy to manipulate. You just set-up a simultaneous buy and sell order with two accounts on an exchange, buying doge for bitcoin at 10x the price. Of course, you're selling to yourself, so you don't lose anything in this process. But you are momentarily creating a price momentum that others may pick up on. Throw some posts in trading forums for all the new people who don't understand anything and just talk about price movements to get-rich-quick, and you've got people jumping on the bandwagon. It's a typical pump & dump and it's the only reason we suddenly talk about ICOs and other coins, because when bitcoin moves up quickly like it has, it's an easy time to exploit all the other coins that have tiny volume / price, but lots of potential eyeballs if you make the price move.
(Personally I believe most cryptocurrencies represent a bubble, doubly so for Ether tokens. Not Doge though, that's going to the moon)