Some of us bring in value by developing existing software packages which amplify the work effort of some critical sector or another. The renumeration for this work is in the form of regular pay. A portion of which should probably be invested smartly.
As software systems grow they turn into complex systems. They become embedded in the processes of the end users, while requiring constant boring work to remain alive.
I fail to see how this maintenance work is less worthwhile than developing new tools. Any complex task requires decades and decades of labour.
This is not to say that identifying niches that benefit from established tecnhinques and require only some domain specific customization would not also be wortwhile.
But claiming "everybody should find such a niche and become entrepreneurs" is quite bit too much. My mental energy is used in my daily work which brings added value to my orgs and our clients. The benefits of this are enormous - I can focus on deep, technically complex work while outsourcing payroll, taxes, liabilities etc. to my employer.
Effectively, I don't think many people can do deep work and become an entrepreneur at the same time. Also, expert skills in one domnain are no guarantee in some other. Star software engineers can turn up shit or stellar business operatives.
I think you are covering the software engineer in some weird halo of infallibility.
That said, I do have enormous respect for people who have created new businesses. But it hardly is the only way to bring in value.