The four fundamental principles of supply and demand are:
If supply increases while demand remains constant, price decreases.
If supply decreases while demand remains constant, price increases.
If supply is static while demand increases, price increases.
If supply is static while demand decreases, price decreases.
The supply you can buy is capped it cannot increase it also stays static as 20 is the max both lead to increases on a supply perspective so your left with demand. Which above you’ll understand with a supply limit
The only thing that brings prices down at that point is a demand decrease. You have no need for bronzes commons after you pull and collect them (which is a higher pull rate) and to a lesser extent silver and gold because they are rarer to pull only reason golds are at quick sale is because of the gold exchange method causing supply to outreach demand. Now when you get to the high tier cards supply is far less available than demand. Once you finally get the required stubs to get an ohtani for example you pull the trigger more and more people will get the necessary stubs thru programs selling duplicates etc which will be all around the same time I think we’re seeing the beginning of that some may or may not buy the missing x amount of stubs when they are close. So in short the max demand for lower tier cards has been reached where as the high tier cards is just now beginning to get reached they will continue to rise until peak demand and then begin lowering.. @teak2112_mlbts