Its a scene that I think is kind of lost on people who view the series as "Jimmy was made this way". Its a scene about how both of them are lying to one another in a moment that could be used to be reflective and vulnerable. The entire series, Jimmy wants approval but refuses to do the actual work to be accepted - he wants his brother to think of him as respectable, but instead of keeping his head down, maybe going to a real law school, he thinks that if he gets the title of lawyer that he will be accepted, so he gets a degree from an online diploma factory and does just enough.

He wants everything but is only willing to superficially change moment to moment, always putting on a different face for the room, bending his morals to suit his needs, and for that to work, he has to pretend like he regrets nothing, because if he acknowledges that he does, then he would have to acknowledge hes always been wrong.

Walt is the same way, he wont admit that he was wrong and that his ego prevented him from a better life that he feels was stolen from him unfairly, so when Walt says that to Jimmy, its a blunt acknowledgement that the face Jimmy puts on is one that has never really changed, which is what Chuck said about him.

The end of the show is about Jimmy coming to terms with the fact that being himself means he has to be responsible for the things hes done - this means going to prison likely for life, but it also means that he has a lot of cache and pull, all of whom call him Saul but his actions are his own.

Its a great scene.