This is a very myopic, eurocentric point of view. Capitalism in the global north is sustained by imperialism. The global south, and its suffering, is what keeps prices artificially low in the global north. This system is crumbling, and disparity is rising faster than ever in the global north as a consequence. Countries like Burkina Faso are kicking out occupiers like France, and BRICS is gaining as the west is falling in relevance.
Further, the UK did not go socialist, unless I'm misreading your meaning. Socialism, as it exists in the real world, can be found in countries like the PRC, Cuba, and former USSR. I'm not talking about welfare.
Further, the US is seeing normalization of socialism. Mamdani may be a socdem, but has implied a far more socialist line, ie collectivizing production. The assassination of the United Healthcare CEO is being met with united support among the working class parties like the Party for Socialism and Liberation are reporting record member growth.
Opinions aren't what drive social change, material conditions evolving and changing do. The material conditions of capitalism in the west are declining, and socialism is gaining. The global south is increasingly throwing off the shackles of imperialism. If you take a very myopic, eurocentric view, then it can be easy to only see companies getting larger and larger and disparity rising, but if you zoom out this very system is pushing the profit motive and capitalism with it to the brink.
The reason the GOP won is because the DNC ran to the right in a country where the working class is increasingly radicalized. The largest block of society outright doesn't vote because they don't see a material difference in the outcome of the election, or because voting in their state doesn't matter as its solidly red or blue to begin with. Both parties support the bourgeoisie. Even if the DNC won, we would still be in the same mess, because the problems with our system is that it's a dying capitalist empire.
The only one supporting horshoe theory is you, as you blame Marxists for the problems caused by both parties in a dying capitalist empire.