The vast majority of the time a car is spending its life parked and not-in-use. If the Model 3 were truly self-driving, it could break that mold and I expect many services will attempt to cash in on multiple drivers sharing a collection of Model 3 vehicles -- if not Tesla itself offering such an option at some point. Why pay $400/month when you could split the cost with multiple users? Unless of course you're spending a lot of your day on the road. Or heck, if you could work it out with your friends/family such that it would work out for both of your work schedules, why not share a Model 3 with a buddy? After the Model 3 drops him off at work, it could come back to take you to work then back to pick him up. Car-sharing services will be in full effect. With the rise of Uber, why not pay a fraction of the price to share a Model 3?