Since I started with bitcoin saw the rapid rise and decrease of the price, so as I read the news and other blogs about bitcoin this is the things that constantly alter bitcoin value.
1. Government policies and regulation (sometimes banning of bitcoin), like Russia, India, S. Korea and others.
2. News and media sites ( closing of related bitcoin site and hacking like $60m cryptocurrency hacked
https://www.wikitribune.com/story/2017/12/11/technology/nicehash-ceo-speaks-out-after-60m-cryptocurrency-hack/27212/3. Intended market manipulation. Some player buy large amount of bitcoin it causes the bitcoin rise in the market.
4. Limited supply of bitcoin not more than 21M tokens, in high demand.
5 Other policy of central bank.
This is few reason why bitcoin alter rapidly.
You mean affect? what is affecting the BTC prices?
I do believe that news Truth or False, affects the BTC prices. You might have pointed out the most common news around and I think some of them are not even new nowadays. They are already expected to have an affect in the market.
That is how everything goes now.
That is why I encourage people to hold so that rich people can't manipulate the market that easily. Or when the government is already involved and they have huge amounts of bitcoins already, I do not know how people working for bitcoin could expect any less depression when government can control the whales by then.