It will keep the grandkids out, and that's all that's intended.
A determined thief can overcome almost anything, including hauling a big fancy gun safe off behind their truck.
I recently tried moving a fifties era office safe from a relatives carport. It wasn’t that big and I could sort of roll the semi frozen wheels.
Thought a two ton engine hoist could lift it a few inches to get it on a flat trailer.
That safe didn’t budge. The hoist got some of its bolts stretched. Have to bring in something better.