They paid $2.2 million; did they know it wasn’t Batman’s first appearance?

A copy of Batman #1 just sold for $2.2 million. That’s insane! Batman #1 was the first issue of Batman’s solo series, but the world’s greatest detective actually appeared for the first time in Detective Comics #27. To put the ridiculousness of this sale into perspective, the most expensive copy of Detective Comics #27 sold for only $1,075,000: less than half of what Batman #1 sold for. I mean, don’t get me wrong, Batman #1 is a valuable book. It contains the first appearance of Catwoman and the Joker and previously sold for $567,625. But if I’m going to pay $2.2 million, I’d rather spend it on Batman’s first appearance. Which leads me to wonder, did the purchaser know what he or she was buying? Did they know that Detective Comics #27 existed?