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?
I vote the number 1 and number 2 as my serious affect to bitcoin value. Regulations that base from government and changing laws about crypto are enough to decrease bitcoin price and also increase bitcoin value.