It's closer to one third of the country, the same third that has consistently voted for unabsolvable evil and corporate interests every 2 years for decades because they mistakenly thought the GOP would lower taxes and that it would make the world better.

As for the exit poll, amounts below 10% are generally considered response bias. There is no way of knowing if that 7% of people voted for Clinton in 2016 and Trump in 2024, but it's highly unlikely given Trump's vote total increased 3% while the DNC candidates declined 8%.

I'm not sure if you were paying attention to it at the time but internal and external forces were pushing the protest vote movement to get DNC voters to disengage and self-disenfranchise. Wikipedia overview link here.