obdurate
A die-hard fan who’s still loyal even though their team is the worst. They’re like a dog who still loves you even after you kicked them.
That Seattle fan still supports the team even after they lost 20 games in a row. They’re a real obdurate idiot.
He’s been waiting 10 years for a win. And he still thinks the team is gonna rise from the ashes like a phoenix. Or a flamingo.
She’s still wearing the team’s shirt even though they lost the last 10 games. She’s more loyal than my ex.