I'd be almost willing to bet that because the cost is so insignificant to them, the WWDC ticket price is almost entirely meant to set a bar for the types of dev

I'd be almost willing to bet that because the cost is so insignificant to them, the WWDC ticket price is almost entirely meant to set a bar for the types of developers that Apple wants to attend the conference. Specifically, professional developers who make money from the Apple ecosystem, to which the ticket price is a pretty insignificant expenditure for the hopeful value that they recieve from being there.