Surely to ridicule the fans of Leeds for believing the club is "bigger" than Brighton and Hove Albion is to commit a category error?
The status of a football club, normally called its "size" is a social construct. It doesn't have an objective reality, it is a product of what we all believe to be the case. And it is not the same as the status of the current team. Teams, owners, fans are all temporary, the club alone, as a construct endures.
There is a lot of debate about gender in the public realm, and how it is also a social construct. So we are told that sex may be biological, but gender is not. And a transgender person is a man or woman, despite their chromosones if they assert they are, and others treat them as such.
I put it to you that Leeds United are perceived by football fans to be a "bigger" club than Brighton, irrespective of whether the latter presently have more money or have a better team. Indeed some Brighton fans themselves have accepted this on this very thread.
So why would Leeds fan be "deluded" for also believing this?
Well, firstly, the fact that you have to keep telling us Leeds is a bigger club says a lot.
But, also, there are many levels of delusion here (and on Twitter) - eg that White couldn't possibly want to stay at Brighton given Leeds are interested, that White's career will progress better at Leeds, that Leeds will be challenging for the Champions League etc etc.