The Rappites were a religious/grass roots organization, but after they failed the town was bought by Robert Owen, an industrialist who wanted to design a utopian community.
A lot people think they know how society should be run; the rich ones just have the power to force other people to play along with them for awhile.
The idea of building a utopian city doesn't need to be a brand new thing for tech moguls to have a greater interest in creating them than other types of contemporary moguls.
Also, I don't think a company town is really the same thing as a utopian city. In my mind a "company town" is mainly an attempt to maximize exploitation of a set of workers, while a "utopian city" is built as a pure expression of some subset of someone's ideals, relatively unsullied by competing ideas, which usually aren't so crass as "maximal exploitation of the residents."
The OP didn't really establish it (e.g. take an inventory of all Americans building utopian cities, and see if tech moguls are over-represented), but I wouldn't be surprised if it was true. The combination of experience with disruptive innovation, engineer's syndrome, and power would seem like a recipe for these kinds of cities, though a less productive one than near-absolute power over some polity.
Also, a lot of the towns mentioned in the comments pre-date tech moguls.
That's kind of what I'm saying. Rich people making their own dream cities is probably as old as rich people and cities. Ig I could see an explosion of home automation tech giving more people a reason to try, though
Not all rich people, though. It might be interesting to characterize the one's that have built a utopian city, and see if they conform to some common type. Maybe they share important characteristics with modern-day "tech moguls"?