Plenty of players at clubs like Brighton have big egos. It's not something that only the players at European level have. Having squad members thinking they're the main man or above it all is a common aspect in football right down to pub level. There isn't a form of uber-ego which only manifests once a team finished 4th or above. They're blokes in a competitive industry, it's gonna be rife at all levels - it's something that Tuchel seems to struggle with, maybe his own ego contributing, despite his path to Chelsea being more in keeping with what you describe.Sure, but this is not how the managers that make it at that level generally get there these days. At a club like Chelsea, you're trying to juggle the egos of some of the most expensive players in the game and some of the most highly rated prospects, which you need to hold onto in order to be a long-run success. This is totally unlike Brighton, where he was dealing with unheralded, hungry players highly motivated to succeed in order to get the big payday. Not all Prem player egos are created equal.
The guys that succeed at that next level generally have spent some time at the highest levels, whether as a player or as an assistant. Klopp is a bit of an exception, but even he had a long spell at Dortmund before taking the helm at a behemoth. For the most part, though, the ones that remain in the top echelon of jobs either played in one of the big fishbowls (eg: Guardiola, Conte, Zidane, Ancelotti) or spent some time at one as an assistant learning from a master (eg: Mourinho, to a degree van Gaal).
He has never walked into a job where he had less job security than the players before, and being a bit of a media darling probably works to his disadvantage in that the London media will be happy to sell the narrative of tearing him down. It's a big transition that most managers fail at unless they take an intermediate job along the way.
Can he succeed? Sure. Is it likely? Not on the evidence.
He has walked into jobs where he has had less job security than the players. He came from Ostersund to Swansea with only the football-hipster seal of approval to fall back on. If it had gone badly wrong quickly he'd have been out of the door very early. Same at Brighton - he wasn't brought in to take them down and build to come back up. Chris Hughton's sacking showed they weren't above showing a manager the door if he wasn't getting a tune out of the players. I doubt any manager goes into a club with more job security than the players.
And the media are always going to be happy to tear down or build up according to a narrative- that's what sells stories. That's not something exclusive to Potter or any other manager who has had his career trajectory. What is the intermediate job along the way? The Moyes Preston - Everton - Man Utd transition?
Potter's Leed's Uni - Ostersund (Swedish 4th Tier - Europa) - Swansea (Championship) - Brighton (Lower-Mid PL) is quite a trajectory and the next step at Chelsea isn't remarkably huge in that context. He is coming into a big PL job with plenty of proven PL experience.
If Potter lasts 2 years there then that's as much longevity as the average Top 4 manager. You'd have to define the parameters of success because if it's lasting longer than 2 years then there aren't many who succeed at Chelsea.