However, if you don't have any siblings and none of your very old friends know anything about technology/startups, you're kind of stuck between a rock and a hard place. (me)

My old friends are really smart and I'd love to work with them, but when I try to talk to them about doing a startup, they look at my like I'm nuts.

I speak from experience. I was in a similar boat. All my closest friends growing up were the wrong fit for doing anything entrepreneurial much less a startup. A friend I met through another mutual friend but rarely talked to turned out to be one of my closest friend and became my previous cofounder. It worked out great.