The more people buy in at lower levels, such as in the 3000s, then the more we're likely to see sell-offs at even quite modest (compared to the ATH) peaks such as the 6000s. As people who buy now can earn a significant chunk of profit selling at those levels, and may decide to do so if they believe the chance of returning to the 3000s is higher than going higher.

There are purchases of BTC all the time, and every time a transaction happens the more we have people who have bought in at current levels, and will base their investment decisions on the price that they paid.