This is a really funny question. Let's ignore the wealth of knowledge and exposure that bankers get from interacting with clients as well as the fact that bankers obviously earn a whole lot more than gatemen/security guards do and just focus on the obvious namely.

1. Bankers wear better clothes: It's the truth, gatemen usually wear shitty clothes and are almost mostly in uniform, where else bankers are always wearing suits

2. Bankers speak better English: Well it's no secret that going to school gives them an added academic advantage, but then again speaking good English is something that's grossly underrated, at least in my country Nigeria and frankly I've never seen a banker who couldn't speak English properly, as for gatemen, it's almost the opposite.

3. Bankers are smarter: Owing to the fact that they deal with and interact with smart people every day, bankers generally end up being smarter than gatemen, let's ignore the fact that academically they are also smarter.

Well I don't know what else to say, I hope you find this useful.