There have been multiple threads over the last eight months discussing this, but I think the mathematical formula to describe this phenomena is:
covid + stay at home + extra time for old/nostalgia hobbies + stimulus checks = high demand for marquee baseball cards
The biggest question now is whether or not prices will come back down. I sure hope prices come back down. I'm a "save up money for long periods of time to buy cool cards" kind of collector. Unfortunately I'm pretty much priced out of the big cards I was wanting to buy some day. Like everyone else I wanted to add Ruth, Cobb, Jackie Robinson, etc. to my collection. Well, I guess I can probably still add them some day....but they won't be in very good condition