Odds of Hanging On
Burnout rates are high in this field, mentally and physically.
There are only so many miles you can pedal before it takes a toll on your body.
Also, the job market is shrinking due to people being able to zap things electronically from their computers. Sure, there is still work, but it's not as much as in the courier golden days.
If you're serious about the job, take care of yourself, and enjoy it, you can probably hang on as long as you can ride a bike.
But we think at some point you're definitely going to want to stop hustling for a living and get a better paying, safer job where you can still ride your bike on weekends.