Because most people who trade by buying Bitcoin are still learning, and some of them still don't understand the difference between investing and trading, so they often think they're the same.
I don't see anything like learning, the truth is those people who trade by buying bitcoin feel that bitcoin is the best coin for trading. majority of this people you feel that they don't understand the difference between bitcoin investment and trading bitcoin know the differences, is just the fear of holding for Long term investment that lead them into trading thier bitcoin.
and sometimes this happens as a result of being curious to make profit from bitcoin, so they feel that trading bitcoin is the short cut to achieve thier target. So is assume that those who are trading bitcoin knows what they're doing.
I doubt if people selling Bitcoin for short term profits that is trading actually know what they are doing, I once shared a story that I read how a man committed suicide because he regretted his actions of selling his Bitcoin too soon on getting to see where Bitcoin has gotten to and he calculated how much rich he could have become of if only he didn't sell too soon and concluded that nothing will ever make him to be that rich in life again and he ended up ending his life just like that, even though that was not a reason to take his life, Bitcoin is not really something to get in and get out too early, it is best for a long term and not for a fewer dollars profits, the future success is not guarantee yet it has the potential to go bullish perhaps it has been bullish if we consider from it's invention.