Intelligence and education are different things. You can't train intelligence - you can teach some tools or frameworks for reasoning and such and that can help

Intelligence and education are different things. You can't train intelligence - you can teach some tools or frameworks for reasoning and such and that can help but some people will understand them and others won't. As a simple example just look at how many people think math is useless. Even having spent 10+ years with people trying to bash it into their heads they still can't figure out any of the infinitely many useful things you can do with math. Education is the result, intelligence is potential. Stupid people have less potential for results. Doesn't mean some of them can't pull a Forrest Gump, nor that they aren't valuable members of society. Just means they suck at learning (at least some) things so their time is better spent doing other stuff.