Factors that influence the value of the bitcoin:
1) government bitcoin policies and laws
2) political situation
3) social trends
4) appearance of new competitors
5) artificial influence on the value by trading at the crypto market
6) news (not always true one)
and many more. Could be something new will appear in the future. Did I miss anything?
Your absolutely right. Even in any investment opportunities, all of this factors will always affect the decision of the investor, seller, buyer. May it be in stocks, forex, etc. The biggest part of this in cryptocurrency are the news going around the policies of certain countries. Well, you just have to do your own due diligence to take care of your decision.
News are indeed the huge factor why the price or value of bitcoin is changing because people are easily getting affected by those things because news can just dictate the demand of a coin from being a good stabilize price to a panic selling scenario where people tend to sell because they don't want to get stuck to that coin.