Because they want to join the bandwagon of the rally and think they could get out before it hit ATH. Only a few made off with profit while a lot stuck with ATH price. If they can't control their greed, they will get rekt.
I think so but i rarely seen those who have been getting profit will be going out from the market as they were putting all of their hopes to get a lot of money instantly.
This will make them all feel panic when the price was going to the bottom again and that's what we have called that as shorting the bulltrend