Do Supreme Court Justices vote?

[Skill and Chance]

The 4 Dem appointees pretty clearly supported Clinton, and Thomas, Alito, and Kennedy (given his personal connections to the family and that he retired this year) pretty clearly supported Trump.  Roberts probably wrote someone in or left the presidential race blank, and Gorsuch was either Trump or write-in/blank, perhaps 50/50 odds either way.

Kavanaugh apparently hasn't voted since he became a judge, so if anything, it appears SCOTUS is losing a Trump voter!

[Skill and Chance]

Mr. Justice John Marshall Harlan II did not vote in Presidential elections out of respect for the principle of separation of powers and maintaining political neutrality.

Byron White, despite being a rather conservative jurist, was a lifelong Kennedy Democrat.

Potter Stewart, a mainstream Republican moderate, voted for George McGovern in 1972, out of his dislike for Nixon, whom he came to despise.

I would not be surprised if Anthony Kennedy voted for Gary Johnson.

Kennedy voluntarily leaving in 2018 pretty much confirms he voted for Trump if he votes at all IMO.