Capital is mobile. From CNBC:
Real estate agents say that the number of multi-million-dollar real-estate listings in Paris has jumped more than 25 percent over last year -- due in part to the threat of the new income tax....brokers say the 75 percent tax on the wealthiest French citizens has contributed to the decision by many of the them to sell their homes in anticipation of a possible move to another country.
"There is a real flow of French people leaving because of the taxes," said Charles-Marie Jottras, president of Daniel Feau Group, the luxury real-estate brokers in Paris.
Link via Harvard economics professor Greg Mankiw.