Why did so many people think Biden would inevitably "collapse"?

[EJ24]

I remember this being a very common theme throughout 2019 and even in the early part of this year. I never quite understood it, Biden was in an extremely strong position due to being Obama's VP, since Obama has gained in popularity since his time in office. He also had higher name recognition than anyone in the field.

People assumed that Joe's gaffes would cost him votes. However, I think most people who have paid even the slightest attention to politics already knew about Joe being a gaffe machine and that's part of the package. It's not something severe enough to turn voters off.

Another thing was Biden supposedly "lacking enthusiasm". But just as Bernie Sanders proved, enthusiasm does not always translate into votes. You can have 10,000 people at a campaign rally, but if only 4,000 of them show up to vote, you can be out-voted by 30,000 others who sat at home that same day.

*knock on wood*

Now we're on to the general election, and he could still collapse, I suppose. But thus far we've seen him endure inappropriate touching allegations, Ukraine/Burisma, the Kamala Harris "bussing" attack, Tara Reade, fake claims about dimentia, and the "you ain't black" comment. He's a much stronger candidate than some give him credit for.