People do understand this is a medical device. What you seem to not be getting in this situation is that Elon Musk is an absolutely horrible human who has a long track record of badness. There are plenty of reasons to be pessimistic that this project will end badly for people who aren’t him.

Awhile back it was discovered that Tesla had quietly programmed Autopilot to disengage if it detected a crash was eminent. Why? Because they were asked to report how many crashes occurred while autopilot was active. Their solution was to game the system rather than actively try to solve any potential problems and be honest / critical of what they had built. This is a system that already has the potential to get people killed. Do you suppose that sort of unscrupulous decision making is going to stop when his people are implanting devices in human brains?