There is that!

But then, outside of being good, lucky, or (probably) both, you aren't going to make much of a living with doing this.  You could justifiably say that everything you do is for yourself, so you might as well make something that interests you.

But that isn't entirely true.  For one thing, there's a particular disappointment when the creation you've slaved over vanishes into the flood without remark.  It doesn't help even knowing that the "fifty more eyeliner colors for V 4.1" that pushed it off the front page also has a lifespan measured in hours.

(Actually...if done properly, I bet a proper eyeliner kit would be useful enough to stick around.  Such are the drawbacks of trying to come up with generic examples to illustrate a point!)

The subtler factor is that doing this can be expensive.  The first time you struggle through painting with The Gimp is when you really start saving for that copy of PhotoShop.  You upgrade your modeling engine.  You keep abreast (!!) of new versions of Poser.  You keep buying new figures with all their associated morph packs so you can build clothing that fits them properly.  And you start thinking hard about Bodypaint and Maya and other expensive options....(oh, yes, and that 16" waccom tablet, and that new flat-screen monitor, and a faster CPU...)

The few bucks you get from a store product may not offset much of these costs.  But every little bit makes a difference.