He lost the 2020 presidential election (concerning which he also lost all recounts, audits, and legal appeals) that was the jewel atop the dung heap of his losing the GOP the House and Senate in his one term as well, followed by the squalid showing of his endorsed candidates in 2022. That's clearly the record of a loser.
The last time one lost the White House, the House, and the Senate in a single term was 1932. Hoover was not so narcissisticly-deranged that he raged that he had won in a "Landslide!" for which no credible evidence could be contrived in any court or legislative body anywhere in the land.