I hope the polling is flawed.
Common sense that these polls are baloney. In order to get those kinds of margins, people who voted for Trump in 2016 would have to abandoning him in droves. Do you know of anyone who voted for Trump in 2016 who isn't going to vote for him in 2020? Of course, it's just my circle of contacts but the biggest difference I have seen is the 2016 lukewarm Trump voters cannot wait to vote for him in 2020.
Do you really believe that any of the 2020 Democrat candidates are significantly stronger than Hillary? She beat Trump by 2.1 percentage points or a little less than 3 million votes. That margin was do entirely to the big margin Hillary built up in California (4+ million). Where are any of them gaining votes that Hillary didn't get? The 9-16 percentage point margins by these candidates over Trump are just ludicrous on their face.