Endorsing candidates with virtually no chance of losing is meaningless. He can't claim credit for making a difference. He's just going along for the ride.
He figures McCarthy is going to win anyway, so why not have that win improve his own win/loss record.
The large majority of his endorsements are for candidates who would have won anyway, endorsement or not. Where is there any credit in that for him?
Because it builds momentum, increases the perception of the power of his endorsement. So, when the endorsement grows in perceived power, at some or several points its ‘power’ will tilt the balance somewhere critical. In politics perception is almost everything!
“Where is there any credit in that for him?”
High information voters like you and me ignore endorsements altogether - we think for ourselves rather than let someone else tell us who to vote for. But 80% of voters are not high information voters, so the endorsement “game” is very real.
In 2024, the down-ticket Republican candidates and party leaders are going to make a calculation regarding which Presidential candidate will have “coattails”. That calculation won’t be based on what they think of Trump - it will be based on what they believe the 80% think of Trump.
It’s the same with product endorsements - if you are William Shatner and you want to keep getting paid the big $$$ for your product endorsements, you will probably want to decline endorsement gigs for products you believe are going to fail, because otherwise your “brand” as an endorser would also suffer.