Did you see that piece about how market vendors send you to the cheap spots?

Ha, this is exactly the kind of thing I would do and then act surprised about. Bleeding brakes is one of those jobs that looks easy on YouTube until you're standing in your garage at 10pm with fluid everywhere and a lever that feels like a wet noodle. The air has to come out somewhere, and a $12 kit usually means you're sucking it right back in through the bleeder threads. Denver being a mile up just makes it worse because you lose braking power in thin air on top of your spongy lever. My guess is you either didn't keep the reservoir topped off or you never got the bubbles out of the master cylinder. Been there, rolled slowly down a hill squeezing a lever to the bar, praying.