A 2-of-3 multisig spreads three keys across devices or locations; any two authorize a spend. Lose one key: recover with the other two. A thief finds one key: useless alone. That failure-tolerance is why serious holdings graduate to multisig.
The tooling has matured from expert-only to genuinely usable:
Sparrow (free, DIY),
Nunchuk (private, polished), and collaborative custodians like
Casa and
Unchained who hold one key and choreograph the rest.