What Apple's Good At

Apple's logo is shown here, very large. This is to drive in the point that Apple is a big, big company. So take note of that.
And yes, my use of a large logo to drive in that point is veyr clever, thank you for noticing.

Apple. It's a huge company (as I cleverly pointed out above). It has been evaluated as the most valuable company in the world, and almost all of its products are in high demand. This is doubly good for Apple, as the products in high demand, are also high in price.
Apple has done what few companies can. They sell a lot, for a lot. Walmart has become rich selling a lot for a little, but only Apple can seem to manage to get customer's to open their wallets again and again. Then they make the customer reach deep into their wallet. Then they make them feel bad about it a year later, and then they manage to make them do it again.
It's really quit awesome.
At least, it is for Apple.

That's what Apple is good at. Getting people to buy their new thing. Even when the thing they have still works good.
I have a MacBook Air from a year ago. At the time, it was the most amazing thing ever. And now, with Apple's announcement of the amazing new MacBook Pro, it doesn't seem as amazing, and Apple has seduced me into adding their $3,000 laptop to my shopping cart. (True, there is no way I can afford it now, but they've caused me to already choose the MAcBook Pro as my next computer, come college time, and years of not spending any money.)
Of course, my computer is no less amazing than it was the day before the announcement, but Apple has managed to make it seem old-fashioned, and not as awesome, because now there is something that is just enough more awesome.
Year after year, Apple announces a new product that is better than yours. It's not amazingly better, but it is just enough better to seduce almost everyone into wanting it.
Now, most people aren't able to give into the seduction and buy a $3,000 computer, $500 iPad, $200 iPhone and other various equipment year after year, but they want to. And eventually, that want, combined with the age of the product they are using, and it's "un-awesomeness" are enough to get them to buy from Apple again, and maybe a little sooner than they normally would have.
For example, if someone buys a non-Apple computer, they will likely use it until it breaks, or is too old to be functional. Then they buy a new one, but not necessarily from the same company.
Apple manages to get people to buy a new product before the one they have is old and unusable, and the new one they buy is almost always from Apple, again.
Apple has perfected the art of making stuff better, but not too much better. They make it so their is enough stuff to make better next year. And then they repeat. Year after year after year.
It's worked since the 80's, and it doesn't look like it will stop working anytime soon.
But will it work forever? The world of tech seems to be full of companies that get huge then disappear. MySpace, Napster. Granted, these are all software companies, and Apple is both a software and a hardware company. Maybe that will allow them to outplay, outwit, and outlast (or however the thing goes, you get the idea.)