What are some possible downsides to accepting a position with a salary that you believe to be too high?
Yes, you can be paid too much.
I know a successful small businessman who paid his employees in "shares" - each of the 3 employees received about 20% of the net income the business received each month.
In slow months, they might not get paid at all, but in good months they'd make a lot.
The employees were doing basic customer service work - answering questions, taking orders, etc. They were making almost 10x what they would make anywhere else doing that work.
This meant they could never afford to quit the company and if the company were to fail for any reason they would be in deep trouble because their skills would never justify that salary anywhere else.
The solution for the employee is to live as if they made "typical" or "high typical" wages, and put the rest into the bank. The extra money can fund retirement or perhaps some expensive vacations, but should never be used for living expenses (e.g. a big house or fancy car)
That requires an enormous amount of discipline.