Basically it is anonymous currency.It is handling by anonymous.As people investing in Bitcoin like that the value of bitcoin is rising.Now answering to your question that why it is increasing day by day who is increasing them simple is that think about your any asset of the market the price of which is increased when the demand of it is increased just like gold so the same is happening in bitcoin that with the demand the price of it is increased.
Yes bitcoin price increased as demand increases because buying will spikes up higher and more will invest. So this must be updated by the marketplace admins automatically and they will be correcting some erroneous price rapid increase which mainly other investors are thingking to it as a bubble price. Don't worry if there were time of fluctuations because that's normal and I am confindent that those bigger whales will just let that price to fall for worst, they will do a price pumps and buy more holdings just to take hold of their assets.
