When you're a billionaire who has material interests in court cases and you just so happen to befriend a justice on said court who has nothing in common with you from either a wealth or personal background standpoint, then you're attempting to buy influence.

There's a zero percent chance that Harlan Crow, a generationally wealthy white guy from Dallas, would ever have anything to do with Clarence Thomas, a middle class black guy from rural Georgia, except that Thomas sits on the US Supreme Court.

None.

Crow sought Thomas out to peddle his influence. Thomas accepted because (a) he believes he deserves this sort of treatment, and (b) there's nothing particularly illegal about it because of how fucked the US Constitution is with regards to high court appointments.

Thomas isn't the only one, either. He's just the one currently in the news.