Not trying to start an argument: what are examples the biggest successes of communist regimes/movements?

Generally speaking, communism usually starts off great for the majority of people. Brings people out of poverty and whatnot. Very, very bad for the rich and upper middle classes but overall the public benefits.

Then authoritarianism kicks in and everything goes to shit really fast. People very quickly lose equality and equal treatment as a result.

Corruption is the biggest, inevitable problem because people naturally want to improve their position relative to their peers. Since that’s incredibly difficult under communism, you end up with lots of quid pro quo. Underground, black markets for anything and everything take hold and become just as important as the main economy.

Basically, it never works out. The end result is authoritarianism and deep corruption every time. Just like other forms of government! Except with communism, the pressures of the system force these sorts of problems to arise much faster.