This website dedicated to info on celebrities says the following:

What “private businesses” are these? A reader raised the question of her finances with us a few months ago when her reported net worth figure was $US 10 million, $15 million less than what it is now. We were dubious, but websites which have a reputation to maintain are unlikely to make wild assumptions. There are people who dedicate themselves to ferreting these sorts of facts out.
What we do know is that she keeps company with some very wealthy people, including Bill Gates, the Clintons, Google and Facebook execs, and of course she has given a lot of commercial purchases (paid for by the Taxpayers) to Pfizer, the top dogs in which are new billionaires. Hmm.

You do not own me bitch witch.
Sadly you would have to query anything from a site that does not fact check its own “facts”, i.e. that Adern is married to Gayford.
Good spotting Dougal, don’t let an alternative “fact” stand in the way of a good good story. As for the “facts” on finances, remember that the figure quoted is just an estimated which will account for the difference between US$10 and $25 million.
Obviously income from salary is publicly available and contributes to only a small proportion of their wealth, whereas private business income can only be an guess or estimate at best.
The income “facts” of Christopher Luxon’s net worth is estimated at around $30 million and John Key has an estimated wealth of NZ$60 million with most of his financial investments held in a blind trust. Of course they too keep company with some very wealthy people.. ah the lives of the rich and capitalists.