If driving for Uber instead caused you to have 500,000 miles on it the bluebook value would be ~$2500, so the extra miles reduced the car's value by ~$1500. By contrast, at 50 MPG and $3/gallon the extra 344,000 miles would have cost you >$20,000 in gas.
When you already have the car as a sunk cost because you need one for yourself, the depreciation is almost completely irrelevant unless you're doing something ridiculous like selling the car when it still has significant market value left.