Historically, people got a big book every year with the name and address of most people in it. You could get unlisted numbers but now everyone has a cellphone which just isn’t broadly published but because now many use it for everything it’s probably not that hard to find.

Also, has others have noted it’s trivial to put other a list of wealthy people. In fact, it’s probably better to skip the Forbes 400 list who probably have some level of private security. Just go through the board member lists of Fortune 500 companies.