I am a Social Democrat in the European sense. There is nothing wrong with the free market per se, but it is the responsibility of the state to intervene with regulation where necessary (e.g. safety), and the responsibility of the state to provide a stable system of social services, e.g. health care, education, housing.
I’ll point to Austria as an example, where social housing is widespread and high quality and public health care is exceptional and pensions are reasonable. With this backdrop, the market economy is appropriate.
I don’t think the unregulated capitalism of countries like the US is sustainable nor would I want to live under that dysfunctional system.