Marx's labour theory of value is only a theory of where profits come from and is largely rejected. Return on captial investment is not restricted to factory owners. All workers get a share of the surplus value and have the option to increase that by investing.
"Capital stands as one of the most influential and controversial books ever written. Its legacy is multifaceted, shaping intellectual discourse, political movements, and the historical trajectory of the 20th and 21st centuries."
My hypothesis is that if you go full socialism, you get stagnation, because no one is motivated to change anything. If you go full capitalism, you get Gilded Age, where wealth and political power is concentrated in the hands of few individuals, followed by Great Depression.