I'm in fantasy land?
If you think the polls aren't manipulated for political advantage you are in fantasy land. You're appeal to 'real scientific data' is childish, since the data can be easy manipulated.
And yet, Trump supporters never had any trouble believing the polls when they showed their candidate leading during the primaries. Every single time, Trump would open his rallies with "have you seen the latest polls?".
When the polls show him to be ahead, it's evidence that the voters love him. When he's behind, it's evidence that the polling is rigged.
Campaigns also conduct their own internal polling which may or may not have biases, but they're not released; they're used for the campaign. So it only benefits them to know what's actually going on. Trump's is one of the few campaigns that seems only interested in good news, and in not learning from what their internal polling tells them.
That said, of course all campaigns will selectively brag about the polls that make them look good, and quietly ignore those that don't.
Again, the polls are extremely reliable in this country. If you can't see that, you're unlikely to be swayed by yet another data point when this election is complete.
When the polls show him to be ahead, it's evidence that the voters love him. When he's behind, it's evidence that the polling is rigged.