None of what you write explains why more people haven't switched into the field, bringing wages down. Other fields work high wages have far larger barriers to entry.
To try to end this on a bit more of a constructive note: think about the difference between the _firms_ that employ software engineers/marketers/salespeople and the _firms_ that employ highly paid folks in medicine and law. How do the unit economics breakdown? In what ways are certain aspects favorable and unfavorable to an investor?
That is, developers build software, then they go to work on the next thing while company can sell existing software.
Each additional unit of software sale doesn't have a developer cost component (unlike for example, shoes, where the labor cost of the worker is factored into making each additional shoe).
Is that close to what you're saying?