I don't believe Thomas was bought by bribery. I don't think any reasonable observer does. Rather, I think that he was friends with a very wealthy person, who appreciates that Thomas is ideologically inclined to give him what he wants.
Nor is that illegal. The illegal part is failing to disclose it. Nobody can say why he failed to disclose it. He has no reason to be embarrassed by it. It's widely interpreted as contempt for the law -- an uncomfortable thing to believe about the highest court in the land.
I know that a lot of lawyers (of all ideologies) have a lot of respect for the work of the Supreme Court. As a non-lawyer, my lack of respect should mean less than theirs. But when a decision comes down to ideology, they can be relied on to vote with their decades-old beliefs, and the entire charade of presenting a case seems unnecessary. The decision could have been written without pretending that they were actually deciding anything.
As you day, democracy is about losing gracefully. But as of now, I'm practically guaranteed to lose for the rest of my life any time it comes down to an ideological issue. That's not corruption; it's the fact that there are at least five justices who I don't believe will even consider it. The fact that one of them doesn't consider a law relevant is an indicator that something is badly aligned, upsetting the balance under which I'm expected to be a good loser.