To me, there are a couple problems of perception that gave Biden/Harris a huge uphill battle in the election that they didn't need to have.

Biden actually did a ton to address problems of inequality and income in America. He worked harder on it than any president since Johnson at least, and scored some huge successes driving up low-income wages and strengthening unions. But, he didn't do it in ways that were visible to the average American, I think because he's so far removed from the present-day average American that he genuinely didn't realize how invisible a lot of his reforms would turn out to be.

His two huge mistakes were:

• Talking about, and letting people in his adminstration talk about, inflation, in terms of "how much have prices gone up this year?" He bragged about getting inflation back down, which speaking from an economist's point of view is accurate. But things are still expensive. To the average American, "getting inflation back down" would have meant that eggs go back down to costing what they used to cost. He could have gotten away with half as much gains on wages, but taking strong action to bring down grocery prices and rent prices. People respond to how much stuff costs, even if they're making 20% more than they used to a year before.
• Focusing all his wage efforts on people who are in the "W-2 economy," even at a low level. The biggest economic victims in the country are undocumented people, people driving Uber, people working at Wal-mart being kept just barely under full-time employment, all of whose rent goes up every year to match anything they're gaining. People are being squeezed out of the full-time-job-having economy steadily more and more every year and into the desperation economy. I know he did the Climate Corps, but something more like the CCC or WPA, giving real full-time working jobs that can pay a decent income on a massive scale, would have been better than looking out for people who already have a W-2 union job having their union more effectively able to fight for them.

And then, also, letting Merrick Garland twiddle his thumbs for four years like the cowardly lump that he is. I think history will look back on this past few years of slow-walking the Trump prosecutions as a massive error that led to untold misery and bloodshed. Honestly, even if he fucked up everything else and lost the 2024 election, if he had simply taken the fire on the roof as an urgent problem that needs all hands on deck, instead of one more renovation project that needs to wait its turn until it comes up in the agenda, it would have been better.