They included The Mikkelsen Twins (who Dane McBeth worked for before he started his course and YT channel), Emeka Ossai (who has his own course) and a bunch of other people- some who concentrated fully on KDP (Ollie El-Gorr stoped promting his "blurbs" course and has gone full on into books on finance and investing) and some who got banned from kindle for life (the Twins got banned, started selling how to and I *think* have accounts again in LLC/family names but are making a fortune on selling their course... last check it was 2000+ members at between $1-5k a go!).

https://kindlepreneur.com/royalty-hero/