It may just be me, but I see nothing wrong in discussing whether a comic book character is insane or not. It’s actually quite a topic in my opinion – even if Batman is a fictional character, he is still one made up of many peoples’ characteristics. Just because Batman’s story is not real does not mean that the situations and feelings he has are non existent in everyday people in real life.
Noting how he has lost his parents, not to mention is one of the richest men in the world/country, that can make you have many a trust issues. Dealing with people at Wayne Industries in the day, and the stress of any sort of dissaproval from Gotham’s public for Batman. It can weigh on a person, you know? Batman is a vigilante, he may have to sacrifice a bit as long as he gets the job done, which is to protect people.
As @markyy said, the costume is extremely necessary. Gotham needs an image to look up to, to look for as hope or as for fear as said. Not some dude that looks just like them. They just wouldn’t take him seriously. The same reason why Superman, Spider-Man, etc wear costumes. It’s necessary. I do not think Bruce Wayne is insane, he’s got quite a clear albeit dark and tortured mind.