I think this happen because more and more of people start sell when they see the price grow, because maybe some of them buy when price was lower and they want to take profit.
That. It really seems that people have started to get used to going up, and then find it strange that the price corrects in a healthy manner. If you want to see the price pump further, you should hope that people cash out profits.
The more people cash out at this stage, the fewer people with cheap coins there will be left to dump the price at higher levels. It basically means that Bitcoin's base value increases with the price that at the same time increases.
The very fact that OGs have dumped a lot of their coins throughout the last years means that they are bought by people who paid more for these coins, and are less likely to dump at a loss.
Some people wonder who keeps selling at $5000 and $4000 after the $20k peak, but they don't realize that OGs got in well under $100 and don't mind selling at these prices. They are still up a crazy amount.