You get tired of having an idea, and no way to capture it.
So, you head over to the local Banjo Mart and the guy behind the counter sells you on how easy it is to record your own music. It sure seems easy enough... plug this into hear, turn this up and VIOLA! You've got a recording studio!
There's a lot more that goes into a professional recording than you can imagine. A LOT more than you can get from a sales guy in a music store.
After you try it for awhile, you'll find out just how much you have to work at getting a decent recording of even the most basic of ideas you have.
...and all you wanted to do was just get something simple to use to capture the ideas you have... not some pain in the butt, complex gear that's gonna take weeks and months, just to get mediocre results from.
Save yourself a lot of hassle... look at something like the Zoom H2 or the Zoom H4.
They're pretty simple to set up and use.
Save your sanity and money for when you DO want a professional recording.