The average person simply can't help themselves and they squander their monthly excess. If they invest they do it blindly and after they accumulate a little money they get the irresistible urge to reward themselves.

I spent time as a licensed advisor before moving to a corporate role. Given my experience I'd say 1 in 100 are successful, disciplined investors if I'm being generous. Sure a lot of people can keep it up for a few years, but for a decade or more? Almost universally no. The rest are better off focusing on debt reduction as they just going to squeak by for decades.