Hi Tim,
I can identify (a touch bitterly, perhaps!) with how you feel ... I'm trying to establish a strong, content-rich site about healthy living for busy office workers, but it's taking a lot longer than I'd hoped to bust through the "clutter" of the internet. I'm hoping my blog won't get lost amongst the typical diet-sites serving ads, posts scraped from other blogs, very poorly written posts, etc...
So far, I've made about $6 on AdSense (though I'm far more concerned about readership than money at this stage.) However, the blog has led to a paid staff position at
Diet Blog 
and a good steep learning curve on the technology side! I've also "met" lots of people I'd not otherwise have come into contact with.
I decided when I launched the blog on Jan 1st that I'd give it a year of posting every weekday, every week, until I gave up. So another 10 months to go before I even start to think about whether it's worth continuing with.
Good luck, and I agree with you that the personal development field is getting crowded. Music sounds like a far better option!
Ali