That is so much more about attitude than bragging. Your smart friends have not been exposed enough or can't put their minds into the mindset of sharing things w

That is so much more about attitude than bragging. Your smart friends have not been exposed enough or can't put their minds into the mindset of sharing things without maybe being afraid of sounding like a show-off. It could be hard to get them into habit of doing so but maybe if there was other people around who'd showcase the "more interesting" way of sharing things they'd slowly change their attitudes. It's hard to describe but I'm positive by slowly introducing elements of "bragging" or maybe in this case just sharing without care the situation would change. It could also be that they just don't have strong enough rapport with you that they'd feel sharing all those things with you, I don't know. Maybe next time tease them with something along the lines "c'mon I know you've been up to something". But take your time, don't expect things to change immediately.