A lot of people misunderstand the uses of a Bloomberg Terminal. I'm a former terminal user. Bloomberg introduced one of the first, and certainly the longest-lasting, social networks when it debuted in 1981. It is a social network whose average user earns more than $400k per year. There's not as many of those as there are Facebook users, but they have very specific needs, they are likely to know and need to communicate with many of their peers, and they consider having a Bloomberg Terminal a mark of status. Bloomberg benefits from the ultimate network lockin. If you work in a financial firm and you don't merit a Bloomberg Terminal, no matter how high up you are in HR, then you're not that important to the company. All those folks are messaging each other with their Bloomberg IDs, so they know with each message who's in and who's out.

For those who dislike Bloomberg's UI, guess what, many people within Bloomberg do, too. But over the decades, their users have learned how to get to their favorite screens by navigating through a pseudo-CLI, and those users do not want to learn something new. Anyone who has ever tried to build a tooling company of any sort knows how hard it is to ask people to swap out one set of tools for another. Your ideal UI for Bloomberg runs directly counter to the deepest desires of their historical clients. Mastering the useless difficulty of that UI, too, means you are part of the in group.

Finally, Bloomberg has set peoples' expectations across work spaces, and it offers many financial firms a standard tooling. Trader X used a Bloomberg Terminal at Firm Y, well, she'll get up to speed quickly with us because we also use it.

[edited to recognize the author understands the social network side of Bloomberg terminals, in line with comment below.]