Not to take away from what yer saying, but LA is the worst example as far as courier work goes. Although it IS congested, it's just different. It's spread out. It's not as concentrated, like Chicago, Boston, NYC etc. I mean, that's why the company you worked for only had one biker. The drivers have no problem getting in and out during regular business hours, so they don't need bikes.
As far as "busting yer ass" I consider making contacts, getting regulars, learning how to do multiple part court filings, in both common pleas, as well as district court, things like that to be where the real $ is. If you are just picking up, point to point stuff you will NEVER make money. If I was still working downtown as a messenger, I'd be in with one of the law firms as their personal runner/docket clerk by now. Not prestigious I know, but like I said, not as soul crushing as the sea of cubicles.
Also, keep in mind, "comfort" means different things for different people. Some people want and need a 9 to 5 with all mod cons, cause they have a family. Some like messenger work, cause yer off nights and weekends, and you can play shows. Some peoples day is ruined if they were out of 2% milk at Starbucks, while others are just happy to be able to have a beer AND have a slice of pizza, instead of choosing between the two.