One issue I see is that many people who DID NOT vote for Trump the last time believed all the horror of what was supposed to come. The whole country was supposed to devolve into an immediate economic and social disaster with chaos and war. But that did not happen. The country actually did pretty well.
There were some very early protests, but that was in reaction to Trump getting smashed on the popular vote but winning due to the features of the electoral college.
That being said, no, it was not a disaster prediction. Trump backed off a lot of his more scary rhetoric at first and most folks who voted against him just signed and figured and took a 'wait and see' approach, me included.
That Trump was so unprepared with his transition team (or lack thereof) did not fill people with confidence. And given his first actions prior to inauguration that
should have been playing to his strengths (I.e. negotiations with drug companies) were utter, abject failures did not inspire confidence.
Once Trump was in office and started almost immediately doing what his white supremacist handlers wanted (Muslim ban, for example) there were more protests.
Yes, the economy kept growing. Trump jumped in front of that parade and claimed he started it, but we've seen time and time again that his efforts either made no difference (coal deregulation) or actively hurt sectors of the economy (tariffs). The stock market spiked upon his election, because it does that when a GOP gets elected, but it settles down to whatever direction it was going at the same rate.
Still, through it all we could see that the man had zero capacity to lead. He talked a big game but was obviously a craven coward unwilling do any actual leading. He'd be fine if no crisis came up. Unpopular, certainly, but still electable due to the EC, a decent enough economy, and the GOP's constant, unyielding efforts at voter suppression.
Unfortunately, a crisis came up. Several, actually but not enough people cared about Puerto Rico or his Concentration camps. We are all suffering from his neglect, his ineptitude, his arrogance, and his complete inability to show any form of leadership.
Now in an earlier post you referred to Clinton outspending Trump, and this is true, but I will also say Clinton's ads weren't particularly effective against Trump. She went for a positive route, which is fine but the ad I saw the most of was a very boring interview where she talked about helping children. Very nice, but ultimately a bit aloof when looking at the Trump circus and not very effective at snaring the "let's see what an outsider can do" crowd away from Trump. More to the point, it was boring. I got sick of seeing the ad. Now Trump can get publicity by being his usual inept self, but without decades of Clinton bashing by the GOP to aim at Biden, it has been coming up short.
Trouble is, at this point most of Trump's voters are a devoted, destructive cult. Ads probably won't make much of a difference at this point. Trump is unlikely to get his 'FBI investigating emails' event but he's probably going to try a 1/2 dozen Hail Mary passes efforts starting mid-October, I suspect he's going to try buying and passing off the untested Russian C19 vaccine as a miracle solution. I also expect him to try a bunch of artificial scandals with Biden and the Ukraine, but I doubt that is going to sway anyone the way the emails
The thing is, he cannot just be beaten. He needs to be crushed. Utterly. This nation needs to say it overwhelmingly rejects him. Anything shy of that and you can bet his appointees are going to do everything to keep him in power until he drops dead.