While the numbers are not laser etched in diamond*, Michael Jackson has sold some 258.9-million albums. This puts him behind the Beatles (289.5 million) but ahead of his first, former father-in-law (well, he would have been had he not been dead for 17 years): 230.6 million. All of these are/were (how do you count when the Beatles no longer exist, nor do either of the two Kings?) pikers compared to Rihanna, who has sold an estimated 334.7 million albums and the 34-year-old billionaire has, presumably, a long career ahead of her.
But back to Jackson. According to Spotify, he has 30,531,780 monthly listeners.
“Billie Jean” has had 1,149,441,023 streams. Consider: the population of China is 1.4-billion people, so it is as though most all of them know that “She’s just a girl who claims I am the one.”
Given these numbers it is safer than houses to claim that there have been a lot of people who have listened to Michael Jackson, either then or right now.