It's simple, and history has borne this out many many times.
In a bad economy, no one cares about your politics if you're the candidate of change. There's a reason why Harris spent two months repeating memes instead of defending Biden's policies, because it's impossible to defend the fact that you had four years to rule and there are more people working 2-3 jobs just to survive.
They knew they needed to appeal to workers. Instead, they spent most of the campaign repeating this meaningless platitude about joy to people who are being worked to death.