The tax is going to hurt a few super high earners such as a few soccer stars, a few pop stars, some investment bankers etc. The figures I have seen are more at 1,000 than 3,000.
So, it will be harder for PSG to attract the best soccer players of the world, and some CEOs, investment bankers etc. will take wage cuts or move, but apart from that I doubt it's going to have any noticeable effects. It's certainly not going to lead to mass exodus of talents from France.