As for maintenance/cost of hardware, I've heard that the LIDAR kit is under $10,000. Given how expensive new cars are and how cheap the same car becomes 10 years later, and given that that's a starting point, I'm not too concerned about depreciation cost.
In the western world there are also already so many suckers willing to pay the initial depreciation by buying new cars and then immediately selling them 5 years later for much less so they can pointlessly upgrade again, so the used car market will be filled with affordable self driving cars a few years after they come out. Like, you can already buy a car for less than the combined value of all its parts, because people put a negative premium on old cars. Why would it be any different in the future?
And given that LIDAR doesn't have moving parts, I'm not too concerned about the cost of maintenance. When you buy a 15 year old car, it's rarely the ABS or ECU or radio you need to replace, it's always moving parts like parts of the valvetrain, transmission, suspension.
And that's if you even use LIDAR. Tesla's cars apparently just use good old cameras. And we know how cheap and reliable those are
Autonomous car price will be higher, maintenance will be higher due to more costly electronics, insurance will be lower due to lower collision rate. Given these 3 unknown variables, how have you definitively concluded car price must be lower?
Finally, your economic argument is incomplete. When renting a resource is much cheaper than purchasing it outright, renting always wins.
Owning a car will be the domain of car enthusiasts, not the typical consumer.