Because it makes you feel good and gives you a temporary high of validation. Same way you can f*** women below your level of attractiveness and get validation from the pleasure they feel. It's pretty simple.
Or to put it more simply, nobody cares about your personal anecdotal experience on Tinder. You are one person, not even a group of people, not even a "most of my friends" anecdote, just a "my experience" anecdote. For the most part you do seem pretty understanding in what is relevant to others generally, but the fact that this is a thread based on a wider scale of experience, and you seem to think your single Tinder experience means something, tells me you don't really care about making a point, just getting across the point you get laid.
From seeing maybe 2 or 3 pictures of you I'd say I'm more attractive than you and I'm in that 20% based on how I see myself in pictures and the reaction I get from females, and also males acknowledgement of my ability to attract. That's not a humble brag, or even a brag, that's just how it is. But I know people don't care about my singular experiences in life as it's based on such a narrow point of view, that it's pointless even worth mentioning.
The only reason I'd have to mention such a thing so consistently is if I needed some validation or acknowledgement from "strangers on the internet" that I'm attractive, when really I'd rather learn from actual wider points of view than give my teasing "I'm no Brad Pitt he he but I'm alright and slay all the time" point of view.