I've got a slightly different problem- I keep finding uses for my wood that are different than what I intended them for. So, I'll go out and get a nice pile of (for example) maple, with the idea that I'm going to make (for example) an entertainment center. As I get ready to make said entertainment center, I realize that it would be a whole lot easier to make stuff if I had a nicer workbench (see where this is going?) and I end up using all of the earmarked maple to make a bench. And so it goes. I haven't bought too many tools in recent memory, but I keep building jigs, stands, and various mechanical devices to make the projects I never seem to get to easier. Right now, I'm designing a jig to cut spirals in turned stock with my router table. I don't need it- I just think it'd be fun to have, and I can't afford enough wood to make a big project right now. Even if I could afford enough wood, well, see above.
Personally, I think it's got a lot to do with the advertising we're all exposed to. You see woodworker X making a morris chair that is quite a lot nicer than you might have the patience for- but then you think, "Hey, I could do stuff like that if I didn't have to waste all this time chopping out mortises!" and pretty soon you're (depending on your media diet) making a router jig, buying a hollow-chisel mortiser, buying new chisels, or practicing your sharpening skills on automotive sandpaper (maybe all of the above). Of course, this sucks up the time you coulda spent just chopping out said mortises and making the chair plus interest- but that's why it's a hobby.
There's really nothing wrong with any of it. Some people seem to like making all their tools perform at the peak of thier condition, and get off on maintainence and restoration. Some folks really enjoy sharpening things. Others will complete projects come hell or high water, whether they've got the tools or no. Some guys just buy tools and let 'em sit in the box for a year or better because they like to own them, or like getting a deal. It doesn't really matter, just so long as you enjoy what you're doing.
Aut inveniam viam aut faciam