SSTAM: to answer your question - think of them like cars:
If all you have to do is get from point A to B every now and then, then you can be very happy with a Yugo! It gets you there, mostly, carries groceries and keeps you out of the rain.
If you want to be a little more comfortable, drive/commute more often, have a little more fun while you're driving - and have the money - you shop around: VW, Peugot, maybe an entry level BMW - it becomes a matter of preference and style as much as anything else - as well as becoming a better driver.
If you are a professional you get a Ferrari - optimized for performance, return on investment as to the jobs it gets you etc etc
I know it's a crazy analogy, but maybe it helps.
Also, along with there being a difference between "cheap and expensive" there is also a difference between "cheap and inexpensive" - there are a lot of decent brazilwood and carbon fiber bows in the US$200-400 range that will take you quite a long way; and there are A LOT of bows in that same price range that are junk.