Marxism works as a critique of lassiez-faire capitalism, but as a standalone system always results in the creation od totalitarian regimes.

Marx never devised any kind of "system" and there has never been a Marxist revolution (if you mean, of the kind Marx predicted would occur). Marx thought revolution would result from the concentration of labour in factories in heavily industrialised countries but so-called Marxist revolutions have only happened in agrarian economies so far.

It turns out that fascism (which is power protecting itself) is the primary beneficiary of crises of capitalism because they happen when labour is at its weakest.