It doesn't seem intuitive, but a BIP39 12 word seed phrase provides around 340,282,366,920,938,463,463,374,607,431,768,211,456 possible combinations, so infeasible to brute force with current tech. But need to be careful with keeping seed phrase secure, making sure you don't forget it, lose it or fall victim to a $5 wrench attack or similar vectors. Multisig may be better.