The Soviet Union lasted for decades and at the time was on the cutting edge of science, math, industry, social sciences etc and became the second leading superpower only 20 years after forming. Pretty successful if you ask me. It took the US over 100 years to do anything similar.

Then there’s China which is looking to be even more successful than that.

Can you name an example of capitalism working

People’s Republic of China. Worlds largest democracy. Largest manufacturing nation - poised to be world’s largest economy. Seems pretty successful