The probability is very low, and that is the advantage of a multisig set up, more security from possible theft of your BTC, but multisig comes with more responsibility when it comes to backing up more things, and someone who does not have enough knowledge should start with a single signature wallet, and advance to a multisig wallet when they understand everything about storing their BTC in a safe enviroment.
Simplicity is best for people who don't have enough experience.
Complexity is best for people who already experienced enough.
Each of them have advantage and disadvantage and each person who has bitcoin must choose a best way to store their bitcoin. If you can be good with security and have good Internet surfing behavior, a single signature wallet can be enough for you.
However, of course a multi signature wallet is better (if you don't buy hardware wallet) but if it is your first try with it, you should use a Bitcoin testnet to practice or if you use bitcoin mainnet to test, only set up a wallet with very small bitcoin amount that is enough to test transaction in and out with multi-sign.
If you practice incorrectly, loss is minimal.
If your practice is good, you can deposit more bitcoin to that multi-sign wallet.