I've never regretted encouraging DS to take chances:
"Sure, go play in the mud" (clothes wash)
"Sure rearrange everything in Daddy's garage into a fort" (good excuse for DH to stop being such a slob!)
"Sure, have friends over" (I would rather have them at my house where I'll *know* what they're doing)
"Sure, dig for dinosaur bones" (The worst he found was what we believe to be an opossum, but it's hard to tell

)
"Sure, read that book" (It may be too hard now, but he may return to it in a few years when he's more able.)
"Sure, take your bike down the sledding hill" (Heck, isn't that what insurance is for?)
"Sure, ask questions" (who wants an obedient, but totally deadened child?)
I would never put him in harm's way on purpose, but I do think that sometimes we shelter our children too much. For example, when DS was 5, he watched his DGM sewing, and asked to touch a straight pin. She told him to poke his finger with it gently to see how sharp it was. Of course he drove it down a good inch into his finger. Caused no lasting damage, but ever since, if told something is sharp, he's careful!
Terri