My only experience using really expensive software comes from the academic biotech sector, in which (for a while) there was a thriving high-end software business, with research groups paying $10K+ for a limited license for DNA sequencing and analysis software, and also software that came packaged with instrumentation, things like mass spectrometers, that cost $100K+.

The stand-alone software for DNA analysis has been mostly replaced by free open-source Python packages written by researchers who didn't want to pay the high fees or deal with things like distributing HASP dongles etc.

On the other hand, writing the software that comes packaged with expensive instrumentation, and that's optimized for that instrumentation, remains a viable business. The cost is bundled into the overall cost of the instrumentation setup. A research group/university that buys such instrumentation expects it to be supported over time, and so that's where low volume high end software production is not really going to change. The software is so closely integrated with the hardware, and software failure has such serious consequences, that there's no way FOSS could ever work in that situation. This is as you say a more business-to-business situation.