The price of bitcoin is determined by supply and demand of the market. bitcoin is a decentralized currency so there is no central organization that determines its price.
I do agree. The price of Bitcoin adjust in terms of demand and supply so that means that the demand in Bitcoin is increasing because the price is rising and vice versa whil on the other hand the supply is limited unlike in centralized coins which you can release a particular amount so that the price would be stable as the demand increases likethe fiat system that we have.
There is no central group, but there is different groups and big whales that can inflict on demand and supply and with that they can't move the price in way they desire. Also we all noticed that bitcoin price at the moments can be very vulnerable on bad news, people in panic are doing crazy things. Bitcoin price mainly depends from us users, and who knows how to deal with community will know how to predict movement of the bitcoin.
I agree with the price is very vulnerable on bad news. But I think the general public is already matured enough not to panic if there is a price swing. You just have to remember that we have a country that backing up bitcoin now, unlike before. Japan is going crazy on bitcoin, ATH also is experienced in term of volume trading per 24 hours. Currently, the demand of bitcoin is very high but will limited supply only, the price is skyrocketing, Everyday, its like new investors or even casual traders want to get a hold of bitcoin for whatever purpose they may have. So its really hard to manipulate the price of bitcoin now, not like before that the Chinese market has a foothold of bitcoin ecosystem. Now, its different, Japan and other countries are really into bitcoin and what a piece of the pie.