I think the price rise was likely down to fradulent trades by bots on gox. It seems gox (or someone else) was actually trading with coins they didn't have and reaping the rewards and then when people tried to cash out they were shit outta look as they neother had the bitcoins or the cash.
Willy was actually raising the price. However the problem with the missing Bitcoins is another story to tell. We can't really tell if someone from Gox took them or people who abused that alleged bug in their system.
Hope, bigger idiot, speculation, bots, Chinese exchanges etc are the reasons give for the rise. It is impossible to say why exactly it went so crazy, it started after Silk Road went down though, so maybe people thought it would legitimize bitcoin and allow it to go mainstream.
The fall has been a realization that the market size and growth isn't as big as people thought. Adoption didn't increase enought with the price, so it fell. Some whales also decided to get out at the top, which stopped any further rises.
One has to realize that the market was (is) being manipulated by the big players. Weak hands tend to be flushed out at a loss. If you've been here for a while, you would have seen a lot of people buying in at e.g. $1000, $800, $600, etc. and complaining that they are at a loss. When did someone who holds a 4 digit number (or more) of Bitcoins come out and complain?
The market should naturally correct as we should have not gone down so low in the first place.