I used to be able to tell people that, back in the DOS era. Unfortunately, in the Internet era, I'm afraid the people afraid they'll break it if they do something wrong are perfectly correct. One quick download of Bonzi Buddy and You Have Lost, for one instance from my own personal network.
It might be trivial for you to backup your computer, but it isn't for most people, and most people don't do it. And, beyond the risk of data loss, people now also have to worry about identity theft and other financial loss if they do the wrong thing on their computer. (Keeping in mind here that for most people, browser == computer.)
That's an advantage of having an old, already-broken car. The potential downside of messing with it is small relative to the potential upside. I've a friend who has a nice BMW he drives every day but he recently bought an old junky Jeep and is rebuilding it in the back yard with his kids. They're a little too young to follow what all the parts do but not too young to learn that cars aren't just sealed black boxes; they're collections of parts that do things which we can take apart and put back together.
my dad used the excuse of breaking the computer to not let me mess around with them when I was a kid. That probably set me back from programming around 7 years or so, now that I think about it.
