"Putting all of your eggs in one basket" is never a good idea when it comes to data. That's not just true of Macs – it's true of any computer, phone, or tablet, be it Mac, Windows, Linux, ChromeBook, iOS/iPadOS, or Android.
Even if your MacBook Air had removable, unencrypted storage, it would be extremely foolish to count on recovering data from the internal drive of a failed computer as a substitute for proper backups.
- For computers with mechanical hard drives, the hard drive itself is one of the components most likely to fail. Hiring a professional data recovery company to try to scrape your data off a crashed hard drive can cost several thousand dollars – and the partial data that you get back (if you get anything back) is often a mess.
- Some early SSDs were known for having firmware bugs that caused them to fail catastrophically, without warning – with no way to retrieve any data from them. It wasn't so long ago that a photography Web site posted an article saying that they could no longer recommend a particular well-known brand / model of external SSDs due to all of the sudden failures and data loss that customers had been experiencing.
There are horror stories about other forms of media, too. E.g., with reel-to-reel tapes, I believe that the magnetic patterns recorded on one part of the tape can sometimes "print through" to the layer wound immediately below. Or the oxide on which the data is recorded can come loose from the flexible plastic tape, with the result being that the data literally flakes off of the tape and onto the floor.
Zip disks (100 MB disks that looked like oversized floppy disks) once looked like an appealing storage alternative for home users who needed more storage than floppies offered, but couldn't afford expensive hard drives. Then came the <CLICK> <CLICK> <CLICK> of Death …
Backups are how you survive catastrophe. But you must make them before the catastrophe happens. Afterwards is too late.
P.S. - Good luck with Windows or Linux. And with learning how to make proper backups, because if you don't back up your Windows PC or Linux PC, it'll be very easy to lose all of the data you have stored on it, too.