One man’s explanation of human behavior isn’t an objective reading of reality, that’s why it’s known as a theory. It’s possible other people, like me, are very familiar with Marxist theory and choose to reject it on a variety of grounds. Referencing one philosopher and noting that it’s strange others don’t agree with them is sort of funny - one could bring up Kant or Martin Luther or Rand or any other influential thinker using the exact same framing.