They don’t assume we have unlimited money, they assume they’ll make enough sales to justify making it (and paying all the people who made it).
Yeah, some companies are making ridiculous profits and underpaying staff. This isn’t some pro-capitalism comment.
Taking things off of streaming platforms or not making old stuff otherwise available usually boils down to bureaucracy and legal stuff. Certain people need to be paid, or have the right to veto their content being sold, or stuff like that sometimes. And sometimes the companies have a legal obligation to either protect their IP or ensure things stay “offline”.
I don’t like it, but I know it’s not always simple.