Many of us knew this but legacy media suppressed it.

"KAMALA HARRIS PAID THE PRICE FOR NOT BREAKING WITH BIDEN ON GAZA, NEW POLL SHOWS.
Twenty-nine percent of non-voters who supported Biden in 2020 said U.S. support for the genocide was the top reason they sat out the 2024 election, according to a survey by YouGov."
[1.15]

So it was not just the working class who "moved couchwards": many decent Americans also moved couchwards.
Will the Democratic party learn from this? No.
But let's keep hope alive!!