You can be forgiven, given the 2016 results. And it is, and will remain, true that Trump could still win this election, despite the impressive hole he's dug for himself.
But perhaps it's worth interrogating this feeling a bit more. The excellent Republican pollster, Kristen Soltis Anderson, has a good explanation (h/t Charlie Sykes at The Bulwark).
“In 2016, emotion infiltrated analysis. Polling had the race as a 3-4 point race nationally, but emotionally a lot of people could not shake the feeling there was no way America would elect Trump and discounted chance it could happen.
In 2020, emotion is infiltrating analysis in the other direction. The polling is clearer and more consistent, with Biden up by 8 in the averages. But emotionally, a lot of people remember the feeling of shock in 2016 and don't want to repeat it. “
Sounds about right to me.