You’re treating democracy as class-neutral. That’s wrong. There is no abstract “democracy” floating above society, every democracy expresses class power. Liberal democracy is the dictatorship of capital: private ownership, capital controls media and institutions, and workers can vote forever without ever voting away exploitation. Socialist democracy is the dictatorship of the proletariat: bourgeois property is abolished, exploiters are politically suppressed, and the working class holds state power. Same word, different class rule. Not “the same hammer used differently,” but qualitatively different systems.
And your “what if someone exploits it again?” question just proves the point. Yes, class struggle continues under socialism. When new bourgeois elements emerge, you suppress them. That’s exactly what proletarian dictatorship exists for. Socialism isn’t a one-time constitutional tweak; it’s an ongoing process of fighting capitalist restoration.
You should really read Chairman Mao and Lenin.