I'm gonna be honest, I don't know if there are any interviews out there where he doesn't talk about his coaching. I don't think it's because Brosnan is full of himself, I think it's because every interviewer asks Sean what he does/what his role is in making such a good team
Plus, I notice you weren't able to link an interview where Brosnan sounds like he's saying NP's success is about him instead of the brothers, as opposed to him and the brothers. I'm pretty sure that's because you can't actually back up your opinion, but don't worry, because I can back up mine:
After being asked about his reaction to Colin breaking 4, he said he thought Colin could do it, then said "He played it out like a pro. He waited, was patient, and I knew he could close in a 56 if he had to, it was awesome". Then, unprompted, mentions how well Lex and Aaron did in the 3k, and says "I'm proud of these guys, they sacrifice a lot, they listen to me and my crazy antics, but I'm so proud of them it's awesome." Maybe you see it differently, but in my mind, I see him praising Colin, then making sure the other 2 incredible performances by his athletes don't go unnoticed, praising them, and then making a little self deprecating joke. Maybe you could try to spin that as him always bringing it back to his coaching, but I think that completely misses the point/context of everything he was saying.
A minute later, after being asked about their potential, he says "You have to believe, you obviously have to have the right talent, the right coach, and I think you can do great things. Nico Young set the precedent for these guys and it's been awesome these last few years". Right there, he's acknowledging that he got good talent, and that he's the right coach for the job, before praising what Nico did a few years ago. Again, if saying "with the right talent and coaching, you can do great things" is enough to make you think he's always trying to make everything about him, I think you are trying way too hard to hate him.