Donald Trump beat Kamala Harris because voters who were concerned about the economy did what they often do—punish the incumbent party during the election.
Because they're grossly ignorant and still believe the debunked trickle down economics theory that fucking Reagan foisted on us all those years ago. And just like every other time they'll act shocked when the economy goes even more to shit and find some way to shift blame to literally anyone but the GOP lawmakers that are plundering their wealth.