I always suspected the cost was a function of the profits of the firms using them.

I think it is a smart move to force bundle the hardware and form the users' keystroke habits over a career. I imagine the switching costs are extreme.

I'm not a trader. I'm actually a programmer and just curious about a lot of things. One day, I contacted Thomson Reuters and asked to try their competing system, I think it was Elektron. It is a pure software system that I got bored with after a few days of exploring.