When price goes down People say xx sold their thousands of bitcoins so price went down
Stupids, if they sold it, someone bought it too..
When price goes up, people say, someone bought thousands of bitcoins so price went high
Stupids, they bought it because someone sold them..
Now tell me why price goes up down.
Typically what happens is people put up 'sell' orders above the market price. Then somebody comes along and fills them, so the price moves when they execute their 'buy'.
The terminology of a 'buy' or 'sell' refer to which one is the market order. Of course there is always an equal amount of limit orders being filled, but the market order is the one moving the market, limit orders cannot move the price directly.