Since you mentioned it a few times, the utopian socialism advocated by Saint Simon (the fight of "toilers" vs "idlers" of *all classes*) is not synonymous with the fight of the *working class* usurping the industrial/financial *capitalist class* for political power.
Engles explained this over a century ago:
https://www.marxists.org/archive/marx/works/1880/soc-utop/ch01.htm
Most of the original Bolshevik leadership of the revolution was murdered by Stalin's regime in frame ups, often because they resisted the encroaching bureaucracy. Trotsky is only the most famous of them as the founder of the Forth International.
