The 2020 DNC primaries came down to Biden and Sanders, who would be taking office at 78 and 79.

Not only does this seem strange for Democrats, specifically, since they are the "youth" party, demographically, but Biden and Sanders are also extreme outliers, historically, 8 and 9 years older, respectively, than Trump (when he took office), who broke the record himself.

Hillary would have ranked #2, barely behind Reagan, if she'd been elected instead.

This is a histogram of US presidents' ages when they took office:

The median US residents' age has been increasing about 1 year per decade, since 1960s (a much slower trend), so that doesn't explain the sudden uptick in candidates' ages.

What's going on here? If someone had asked me in 2017, I'd predict the opposite societal trends, because of social media that worships youth more than old media (TV) did.

Two plausible explanations that I can think of:

• social media and smartphones somehow had the opposite effect (If so, how?)
• DNC wants to look like it's putting up a fight, but it actually wants to lose (I'm not saying I subscribe to this theory, but it's popular in some circles)

but maybe there is something else.