If you buy an ordinary vehicle in Tesla price category and then drive it as an Uber yourself, you can pay off the price of the vehicle and earn yourself some money as well. You would also have to deal with all the same risks and maintenance.
If you remove the "driving vehicle yourself" component and have it drive itself almost for the entire day, on it's own, while you're busy with your own stuff, how can it become a worse deal?
If I buy a Tesla and use it to do Uber driving, I am there to protect my asset. I am making the decisions about whether to use FSD or drive on my own, depending on the location, weather, etc. I have a degree of control over the rides I accept and the places I go. I can have some of my personal items in the car because there's never really a time when the rider is there and I'm not.
If I buy a Tesla and put it into robotaxi mode, I am not there. I am not making decisions about how the vehicle should be operated. I am not in control of ride selection. I can't use my car to store personal items, unless I'm OK with the risk that they might be stolen.
There's a huge number of problems that could happen to any robotaxi vehicle. When that vehicle is part of a fleet, it's no big deal to the fleet to lose one vehicle. When the fleet is owned as a unit, the costs of those problems are spread out.
As an individual owning a vehicle that intermittently joins a fleet, the fleet still feels the same way about my vehicle, it's no big deal. But losing my vehicle is a huge deal to me. It is not a class of risk I would want to take on unless the revenue is insanely good, or Tesla finds ways to assume the majority of the risk and minimize the financial and convenience risks I have to take on. Both of those paths substantially impact whether it would be a viable business for Tesla.
The only way to make it a good deal for Tesla is to make it a shitty deal for the vehicle owner, and vice versa.
If you remove the "driving vehicle yourself" component and have it drive itself almost for the entire day, on it's own, while you're busy with your own stuff, how can it become a worse deal?