I don't know what is going through Bill Gates' mind, nor do I care too much with regards to Bitcoin. He is only 25 years younger than Warren Buffett, but he is a billionaire and he isn't one of those people that "needs" bitcoin. He has so much money that he could probably find a way send it to North Korea without using bitcoin or cryptocurrency and find a way to conceal it – and if he were to be caught I'm sure he would only get a slap on the wrist.
Without lingering on any billionaires in particular, when they reach that status, they have access to financial services that you and I do not. I don't want to put the Winklevoss twins on a pedestal that is any higher or lower than Bill Gates (or vice versa), but I'm pretty sure that both parties can get access to better banking services than 99% of the people who are browsing this sub right now.
The kind of way that we hold idols and their remarks towards something is entirely unimportant because it changes nothing. Maybe it's a technology thing. Who knows? I've been buying bitcoin since 2017, but didn't start using uber or uber eats until 2021. Last but not least, I don't see the reason why a billionaire would need bitcoin in this lifetime.
Source and link to Reddit topic: Satoshi said, "If you don’t believe me or don’t get it, I don’t have time to try to convince you, sorry." This applies to both billionaires that are non-bitcoiners and alt-coiners.