I don't think Marx always intended revolution and the term changed context later in his life, when reformation and revolution were distilled as two separate approaches. In my opinion this is still a fault line in modern leftist movements.

Capitalism rewards the vicious rentseeker and punishes the virtuous worker.

Any transfer of wealth towards weaker member of society is forbidden? Should we let babies starve, after all they don't literally pull their own weigth? What about disabled people?

This is completely wrong. Marxism is presented as "scientific socialism" compared with former idealist versions that proliferated in the 1800s. While you can disagree with his conclusions, Marx presents a theory of class society, of the development of productive forces, and how these interact to advance the political forms of society which ends in revolution when the old structures and the new engines of society clash. He doesn't really go deeply into what "socialism" would look like, only that the clash between the bourgeoisie and the proletariat, where the proletariat both massively outnumber the bourgeoisie and do all the work for survival wages presents a contradiction that will be resolved.