It's really not a big deal. I would never not put up a tree or gate it in like a prison b/c of kids. Animals...maybe.
Just tether it w/ fishing line if you are worried. It really will be fine. We've always had a huge 8' real tree and have never had an issue. My kids love it, it's pretty & sparkly. We do non breakable ornaments on the bottom third and thy are allowed to play w/ them.