Or, in other words, unless you really know what you're doing, you're probably wasting your money.
For myself, I tend to buy the cheapest item available of any category until I understand why the other ones are more expensive.
I did the opposite and started out by buying one of the more expensive consumer-level dSLRs (a Nikon D7000) without having a clue about photography. The idea was this:
a) A camera like that will not be the limiting factor - my own skills will be
b) It's expandable by a myriad of objectives and accessories if I want to get more advanced
c) If it turns out this photography thing wasn't really for me, I'll still get great vacation pictures with the auto mode!
I think some hobbies are just like that - you can't have gear with too poor quality or it will affect your experience so badly you'll lose interest. Learning to play the guitar on a cheap guitar that can't keep the tuning sucks. Learning astronomy on a cheap toy-level telescope is just as bad. Photography might be a different beast, but to me it seems you can't go wrong by buying quality gear from the outset.
I expect less than half of those who have learned to write are actually able to do so.
Wait a minute, how did you come up with this figure? If you can't write an actual letter that is sufficiently intelligible to serve a simple purpose, then by any reasonable definition you can't write. Are you saying half the people who have learnt how to write have since forgotten it, or that they have a level of writing that isn't even sufficient to compose a letter? I don't buy that. If you've learnt how to write, you can write a simple letter.
This isn't off topic either, because the analogy carries over to programming. If you've learnt how to program once, then you can probably use that skill for simple tasks like writing VBA macros for Excel. It doesn't matter if you don't know the exact syntax - you can always search the web for that - but the basic knowledge of variables, formulas, loops, how code is executed line by line, how to step through the function to debug and so on, that's something that far more people than actual programmers can use. I should know - I'm not a programmer and I wouldn't know how to write a standalone program that could do anything remotely useful, but I do save a lot of work every day with my custom-written macros.
Because if we save that botle of milk long enough, it won't be worth drinking.
And that, in this case, would be the best thing that could happen.
What makes you think the car was a "bad example"?
Something like this perhaps? http://newcovermagazine.com/2010/08/23/going-no-were-chinese-traffic-jam-enters-9th-day/
Blessed be those who initiate lively discussions with the hopelessly mute, for they shall be known as Dentists.