How do we know? Because the entire Motown Music catalog sold for a paltry $61M.
Philly Soul sold to Sony Music in 2014, no price available.
But check this out. The top selling recordings all time are music created by whites. Not one black recording among them.
Perhaps black music was “popular”, but only via the radio? The facts don’t lie. Whites did not purchase Black music in large quantities.
No matter how popular it was, it didn’t actually sell in huge numbers. Blacks bought black music, but their purchase numbers could only reflect the numbers of their small population. Facts.
https://www.statista.com/statistics/271174/top-selling-artists-in-the-united-states/#:~:text=Perhaps%20unsurprisingly%2C%20British%20rock%20band,Presley%20with%20139%20million%20units.