If this use of Find Familiar to let a pet steal baubles breaks your game, then I’d say you have an overly fragile game.
Baubles?
Baubles???!
You think I'm going to waste this once-in-a-lifetime opportunity on mere baubles?
I mean, really. If it's small enough for a raccoon to pick up, it's mine. Your jewelery, your gems, your expensive incenses, your small-size magic items that you don't wear at home while sleeping, [edit to add] your scrolls, your important documents: all mine, soon enough.
I case the place during the day. Then at night when all the lights are out I saunter up to the wall and summon good ol' Rocket Raccoon to appear on the other side of said wall. Rocket scoops what goods he can carry, then I put him into the extradimensional pocket and re-summon him such that he appears at my feet. Unload him. Repeat this process until there's nothing of value left to take. Repeat each night at a different site until the hue and cry gets too great, then move on to the next town and start over.
Now in 5e this might not be so much of a concern as from what I gather there's precious little (by RAW) to spend your hard-earned money on; but in any other edition of the game being the wealthiest character in the party (and maybe in the whole damn kingdom!) by a factor of huge is going to throw in-party balance completely out the window. And that's where things get broken.