Sean Penn has been a powerful activist for Haiti, helping to raise millions of dollars in aid — but he believes more money could be made.

Penn’s annual Help Haiti Home gala raised $6 million this year, but only a fraction of guests are supporting the cause: “There are a few extraordinary people that come, but then you have a room that is full mostly of people that are not giving anything,” he wrote in the latest issue of Haute Living

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Adding that the guests can surely afford to part with some money: “They eat, stargaze and watch the band but, honestly, I don’t think there’s a person in that room that can’t afford $25. I always wonder about that.”

Penn, 56, began his work in Haiti six years ago — taking a two-week trip to help distribute medication in the crippled nation. Those two-weeks suddenly became nine months: “[Someone told me,] ‘don’t stay more than three months in a disaster zone without taking a couple of weeks off’… I made the mistake of not taking that advice. I think I went a little kooky.”

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The island nation captivated him: “[Once you] start to get a feel for the place, [you] know you’ll never really know the place. [You] know that you’re going to have to use your best instinct[s] about who to trust, who to learn from, who to question, who to challenge and be challenged by. It’s a long process, but we’ve had a lot of success.”

The “Milk” star founded the J/P Haitian Relief Organization in 2010. It began as an emergency relief organization made up of just 32 Americans and has now expanded to nearly 200 mostly Haitian members.