Absoltuely, yes. People can find happy moments in almost anything: even in warzones, as slaves, as serfs under feudalism. Humans can always find individual happy moments, we are good at that as a species, but that is very different from our circumstances allowing us to be generally happy. I would never even begin to argue that slaves are generally happy as an example, but that doesn't mean that they didn't find brief moments of happiness with those around them.

I don't think capitalism even precludes some people from being generally happy in certain circumstances if I am being perfectly honest. However, there are socialist systems that allow many more people to be much happier, and that is something I think is worth striving for.