Government regulation will determine the popularity of bitcoin and hence will affect people's demand, so it can be said that regulation is the main factor affecting bitcoin price. If all governments accept and legalize bitcoin while encouraging people to use bitcoin. I believe that will trigger a crazy bull run for bitcoin and we will even see $1 million per bitcoin. But that won't happen anytime soon as governments are still not really friendly with bitcoin, they are still wary of it because they always think its decentralization will harm their centralized system.