From Feudalism to Mercantilism - the path to real wealth

When the only economic structure is feudalism - the wealthy need only pay attention to becoming even wealthier whoich is defined by REaganomics and "free markets" - merchantile societies will be easy winners in the economics game.

Why does capitalism - the ability of individuals to invest in new businesses in socities wealthy enough to afford individual decisions - work well with mercantilism or using resources to create greater societal wealth?