But we know not many people who can buy low and sell high, and many of them have big greediness in trading, so they want to make a bigger profit.
As long as people think the price going up means Bitcoin is doing well and the price going down means Bitcoin is doing bad, nothing will change. These people only pull the trigger after having seen the price go up a lot.
By the time they gained enough confidence to pull the trigger, they usually buy around the peak of a bull run or rally. It has been like that in the stock market as well--average joes are average joes in any type of market.
As for the greed, even the best traders struggle with that. It also heavily depends on someone's mood, so regardless of your skill level and market understanding, if you feel shit, you can't make rational trading decisions.