Why do people who call out capitalism for being a broken system, fail to acknowledge socialism (in all of its purest forms tried so far) is also broken and does

Why do people who call out capitalism for being a broken system, fail to acknowledge socialism (in all of its purest forms tried so far) is also broken and doesn't work when you have non-altruistic self interested humans in the mix or at least people who will look out for others but mostly people in their social proximity. I'm all happy for an alternative, and something better than capitalism. but at least suggest a working alternative. Capitalism for all its faults seems to have the highest chance of success, especially when you hybridize it with some socialist policies which is more or less what most western countries have done and even then there are basic issues, but neither extreme capitalism or socialism works. Both have a tendency to encourage different forms of corruption and different levels of inequality, or just short lived gains.