He purchased each plot for between $5 and $15M. The article describes the residents as "Doctors, lawyers, business executives and Stanford University professors".
These weren't inherently $15M properties - obviously price is no object for him and once he started buying adjacent properties the prices went way up. Zuckerberg paid $14 million in 2013 for a 2,600 sq ft house that was valued at $3.17 million [1]
As far as whether they're "regular people", depends on perspective. Relative to the US / world, a net worth that includes equity in a $3M+ house is an outlier but most of these people live what would have been considered a typical "upper middle class" lifestyle a couple of decades ago [source: me, ex Palo Alto resident, still have friends there]. Putting a couple of kids through college has become insanely expensive. They don't have compounds in Hawaii or fly around on private jets.
Okay, but it doesn't mean they're regular people. Owning a single one of those plots out them in the 1% of household net worth, even if they had 0 other assets.
Ok but what does that contribute to the conversation? I think a good enough definition for regular people is if the average person can achieve that title with talent and hard work more than luck (not that luck doesn't also play a major factor). Whereas becoming a billionaire has a lot more to do with luck than hard work (even though hard work still plays a factor).
The gulf between well paid white collar workers and regular people is so massive which is "closer" depends mostly on which billionaire you're measuring.
That doesn't pass the smell test. Outside the inflated prices paid by Zuckerberg the houses were worth around $4 million, which likely would be around be most their main net worth (let's say it is 5 million). The median net worth in the US is $200k so let's call the the cut off for "regular person" (by that definition >95% of people on HN would not be regular). So the gap from the millionaires here to "regular people" is a factor of 25, in contrast the factor to the smallest billionaire is 200, so no what you say is simply false.
I would not call these "regular people"