Let’s not get ahead of ourselves. Relative to something like Microsoft Office they’re tiny and we have open competitive solutions there (a product notorious for a billion corner cases).

And let’s not forget “EDA software” was single handedly pioneered by one woman and some lisp. Before then, it was hundreds of men taping out circuits on 4x8’ ply with...physical tape who all complained the labor and complexity costs were enormous and nothing could be done.

If we really want to point fingers, we could say it’s a monopoly on the supply chain side of manufacturing - costing millions in NRE’s to make a chip - but if you are willing to scrimp on process size you can get it done for $3 per layer per reticle at 500nm scale and $50 per mask.

To make things more concrete than "big" or "relatively...tiny", some quick googling puts Cadence's annual R&D spending at a little less than $1B and Synopsys's around $1.2B. Mentor Graphics is part of Siemens, so that'd be harder to figure out.

It’s a strawman. I never used “big” in an absolute sense, so it’s implied that I meant “big” in their field.

Since you seem to know, what company would one go to for fabricating a 500nm chip these days at that price?

500nm feature size is positively ancient. Any of the myriad fabless companies won't even care about those dinosaur technologies.

I would try the local university with an electronics program.

Are you seriously trying to compare document processors to state of the art EDA tools?