It depends on the polls you're talking about.

Polls saying that Trump's matches or beats Biden's right now doesn't prove that he'll win or even be nominated.

But polls (like the 2020 election) that show his incredible popularity, which seems not be declining in spite of everything so far (adjudicated sexual abuse, adjudicated decades of fraud, admission of stealing nuclear secrets, a call for General Milley's execution) surely tell us something about the public that's far from "meaningless."