Is there a way not to stake security on a single private key?
One detail: Bitcoin supports multisig at the transaction script level itself. Two common address formats are P2SH and P2WSH.
Multisig can't stop all signers from being tricked: if everyone confirms without carefully checking the transaction details, even the highest threshold is useless.
Remember this instead of memorizing a bunch of jargon. Download wallet software on your computer only from official sources; don't install packages sent by other people.
Looking at the market: $BTC is quoted at 73426.33 (24h -0.42%).

What I say may not be right, so don't follow it blindly.