The same thing goes for cheaper phones. Apple has made some phones that were a little bit cheaper than the flagship phone, but most people still buy the more expensive phones if it’s not the most expensive, it’s the next one down that most people buy.

Funny then for them to believe that foldables would sell more...

They sold just fine. They just didn't sell a billion million units, so in Apple land that was considered a "failure". Most manufacturers would've been stoked to get the sales figures the iPhone mini got.