[bike_index]

1. Reporting stolen bikes makes it harder to sell stolen bikes, making bike theft less profitable - and ultimately making it less likely that you'll be looking for a good deal on a new bike, since your old one won't have been stolen.

2. Some people actually do care.

3. Buying stolen property is illegal

[DrJ]

isn't (3.) 'knowingly' buying stolen property that is illegal? but 'unknowingly' buying stolen property would at worst mean you will have to surrender the property to the original owner?