No, not the stat, but I think it’s indicative of a certain proportion of the American public being delusional. Everyone should see that Trump is the likeliest winner as it stands. That doesn’t mean he will though.
It also points to things like the enthusiasm gap. Sure, that’s a thing. But any Democrat-inclined voter who actually turns out to vote and is faced with a choice of Biden or Trump will vote Biden. They just will. And anyone who doesn’t turn out to vote wasn’t that arsed anyway. The unique thing about Trump is he’s got his thought vacuums who will vote for him regardless, and he’s got a certain proportion who will note against him regardless, because they are so repulsed by everything he does. That’s not necessarily different to any other election, but it might be amplified.
I also think it’s a bit erroneous to compare where Biden is to where Clinton was at the same point. It seems to suggest that because Biden’s lead is smaller, he’ll experience the same collapse in support as Clinton. Not necessarily. Also we live in different times, and American voters might have different priorities. Who knows.