Ironic as I went the other way. I was a Communist when I got into FOSS and as I got older I realized I could never defend the historical record of Communism.
The ideas are why it failed. Thats the core problem. Marx believed he could build in essence a church of Communism that would be incorruptible zealots who would lead society to Communism. A dictatorship of the proletariat led by an enlightened few who could teach and reeducate the masses to live in productive harmony with one another. And that, for many reasons, never works.
Lmao source please? For the church/zealots-part. Also I don't think you understood the concept of the dictatorship of the proletariat and the way Marx uses language to get his point across. Maybe you should read more secondary literature?
You don't have to, but you should. Lenin and Mao practically worshiped Marx and they both attempted to implement his system faithfully to the spec he advocated for. And I know that viewpoint is somewhat controversial in non-Leninist/Maoist circles but I think it's true.
What's more I think the historical records of economic collectivism outside of Socialism and political Authoritarianism outside of Socialism are numerous and expensive enough to justify an opposition to Communism as a system.
I think the main realization that made me nominally support Capitalism is it's performance in a "degraded" state. You can have the absolute worst scenarios (think Pinoche Chile) and Capitalism provides constant incentive to improve things and doesn't seize up in the meantime. It continues to function even in the face of severe inefficiencies.