i think BIG money might have something to do with it too. BTC got the attention of people with deep pockets.
The Bitcoin float is waaaaaaay too small at current prices to accomodate any meaningful or material amount of capital from 'BIG' money. Consequently, if any HNWIs, hedge funds, etc. want an asset that cannot be seized, inflated, confiscated, is not subject to counter-party risk, is increasingly liquid with exchanges coming online, etc. then they will have to keep paying increased prices. For some comparability to other assets, economies, or currencies just see this infographic from
RunToBitcoin.