There is one very important thing missing here. There is no mention of any relationship with the Lord. Without that, nothing else matters. You can be a very "good person" and still be lost for eternity.
That’s because he doesn’t have one. His parents were Christians. He’s read the Bible and unwisely is not a believer. It’s probably why he’s a supporter of liberal politicians and their views. He was a big Hillary supporter. So with Buffett, we have to eat the watermelon but spit out the seeds. Listen to what he has wisdom on (investing) and not listen to anything he has to say on God/church, political views that are influenced by his values etc. his billions won’t get him to heaven. So here on this earth is his only heaven, unless he changes.
It's hard for a rich man to enter the kingdom of God.