First one has to question what criteria they are using to determine who is a millionaire?
If it includes real estate and immovable assets these things are hard to move out of state and therefore discourage relocation of the owner.
Also take in to consideration that inflation in the last ten years has driven many peoples paper wealth up. People that 10 years ago would have been worth 700 to 800 grand are today millionaires.
On paper my wife and I are millionaires. Trust me we live very modestly and do not consider ourselves wealthy. We are comfortable but in no way wealthy. Most of our wealth is wrapped up in retirement funds so most of our wealth is very limited in what we can do with it and always under threat of confiscation by government.
Being a millionaire doesn’t mean what it used to mean.
If it includes real estate and immovable assets