It's not something that happened by accident.
People like it and gravitate towards it.
Doing one, and preferably only one thing is really comforting.
When my friends who live in the city complain that their sink is backing up and how hard it is to get a plumber even after offering $350/visit, I listen to the symptoms, figure out the tools needed, pay a visit and fix the problem.
When I tell them how easy it is to diagnose a plumbing problem, and how next time they don't need to pay me in beers or even the plumber - they are just. not. interested.
Writing the same React application a 100 times is far more enjoyable (and profitable).
People really like to say they want to do more things in life, but when push comes to a shove, doing the same old thing, repeatedly, is extremely comforting.
Doing different things is risky and non-comforting.
That takes deliberate practice and planning.