Flat earth and socialism are both discredited concepts that ignore scientific and economic evidence.
Karl Marx is primarily known for his contributions to sociology and philosophy rather than economics, and his ideas have limited relevance in modern economics.
Hans Herman Hoppe is a renowned Austrian economist. Despite being from the same school of thought, he has been a regular critic of Hayek. Hayek’s probable most important discovery is the “knowledge problem” which says a single person cannot have all knowledge to make decisions as knowledge is dispersed and decentralized. Being on Mises’s side in the Socialist Calculation Debate, Misesians don’t favor Hayek’s argument and see it as not important for the debate.