How many countries even follow Marxism? Most communist nations don't even follow what Marx wrote. China, for example, has loosened it's communist ways, introducing capitalistic principles, and seen dramatic growth over the last decade plus.
Capitalism isn't perfect. Literally no one believes it's perfect. Read some Joseph Schumpeter, he explains it well.
The bottom line is that capitalism outperforms marxism every single time, hands down. Ask the Soviets if I'm wrong.