This is akin to the classic argument that no one has gotten communism right, and in theory it's a good model. The reality is that humans are going to human, and some things do not work at scale because humans will inevitably do the human thing and some systems just aren't designed well for human behavior. The insistence that people just aren't following the definition that you've chosen disregards how words come to be - people create them to describe something new which was not previously defined, and they are generally created on the fly by people, not by people sitting down and writing out a specific definition before publishing and/or using it. Definitions also change, over time, to reflect how the words are being used or how the world itself has changed.

With all that being said, you did ask for sources on how capitalism plays out in the real world in response to people abundantly telling you that capitalism is harmful, so here's a few sources you might find interesting that approach the harms or outcomes of capitalism as it has played out in the world in various countries.

1. The Impact of Advanced Capitalism on Well-being: an Evidence-Informed Model
2. Capitalism, socialism, and the physical quality of life
3. Testing hypotheses about the harm that capitalism causes to the mind and brain: a theoretical framework for neuroscience research