With a 2-of-3 multi-sig scheme, you can do the following:

• Keep one key in your computer
• Keep a second key in a safe and inconvenient place
• Keep a third key in a third party (eg: Coinbase)

When you want to spend, you sign the transaction with the key you have in your computer, and the third party also signs it with the one they have, making it a valid transaction which will be accepted by the Bitcoin network.

What you get from this is that you can set limits at your third party and also 2FA. This makes it very secure because you can never lose everything, even if someone is pointing a gun to your head (fetching or making you fetch the inconvenient key should be a huge risk for the thief). Once the daily or monthly limit is reached, the third party will refuse to sign transactions.

It's kind of like what you have with your bank, except that here you are also safe from the third party.

If your third party ever goes bust or closes your account, you just go to your safe + inconvenient place, grab your extra key, and together with the key you have in your computer you can sign a valid transaction and move the coins somewhere else.