Going for more than 100% markup is asking for govt intervention to break up the monopoly.
To clarify this a bit, monopolies are perfectly legal. But with monopoly status in one area comes the obligation not to abuse that position in a different area. This was the basis of the Sherman Anti-trust Act in the late 1800s. ("anti-trust" -> "we trusted you not to abuse your power"
).
The case I'm most familiar with was the breakup of AT&T. They had an effective monopoly on all telephone services, but they (allegedly) abused that in two ways: 1. They got into the computer industry, selling their own computers and the Unix operating system, and 2. they had an effective monopoly on "the last mile", the wires going into homes and businesses, and used that to keep the long-distance business. Historical aside: how many of you knew that Sprint stands for "Southern Pacific Railroad Internal Networking Telephony"?
Another example was the "browser wars", where Microsoft had an effective monopoly on the operating system, and tried to make it impossible to remove Internet Explorer from the system, hurting other browsers. They didn't have to break up the company.
I would argue that Tesla isn't even close to having a monopoly position, even if you ignore non-BEV cars.
Having said that, if FSD is really the only truly usable self-driving technology (or even just dominates, say 90% of the self-driving cars), then insisting that owners can only rent out through Tesla's network would be a pretty clear restraint of trade action.