Suppose That You Overheard the Following Statements at a Conference

Suppose that you overheard the following statements at a conference for institutional investors:
(A German national): "My money manager knows the German firms very well; why should I bother to invest in French and American shares? I am not familiar with their names or their operations, and I will have to pay much higher costs to buy them."
(A French national): "Why should I buy German and American shares? The foreign brokers will give preferential treatment to their domestic clients, and I am going to get a lousy deal in terms of prices and costs. Furthermore, I can't read the financial statements of these companies, as they are written in German or English, and with different accounting methods."
(An American national): "I can't even pronounce the names of these foreign companies; how could I defend investing abroad in front of my board of trustees? By the way, what is the capital of Switzerland: Geneva or Zurich?"
How would you try to convince these people to diversify their portfolios if you were the marketing representative of a big international money manager?