I never found dynamite, but I once found a box of 40+ year old road flares in a friend's garage that almost made me have to change my shorts. Working at some rocket companies that were run by amateurs, I have found stuff that makes dynamite look pretty tame. There was one company where I found a box with bags of powdered aluminum on top of a plastic tub full of ferric oxide just sitting on a shelf. I'll let you look that up if you don't know what that makes. At another company I found a bottle of a hypergolic chemical that the Germans had tried in their rocket program and quit using it because it was too dangerous. When I found that I walked into the boss's office holding the bottle and asked her "Do you know what this is?" Then I explained what it was and asked her what they were doing with it, since the Nazis in WW2 thought it was too dangerous to mess with!
I know this is now way off topic, but after that experience the risk of making BP isn't really such a big deal to me. I guess it's about how much risk you are willing to take, as long as you don't take anyone with you.