This was on HN a couple of weeks ago. I think this response is great.

What makes a senior dev?

Mistakes, rewrites, late nights, firefights, and deadlines.
Core dumps, memory leaks, hardware faults, and plain bad luck.
Big O, data flow, always learning – or out you go.
Manager metrics, schedules hectic, methodology hegelian dialectic.
Taking the heat, feature creep, open office, uncomfortable seat.
Holy wars, revolving doors, carpal tunnel, all you can take? There’s always more.
Fucking suits, random reboots, and the ever present “thousand language stare”.
Oh yeah, pressure – lots of pressure. And time, time, time.
Metric shitloads of time.
Time, man. You gotta do your fucking time.