A non-profit is still a business. Success is necessary for existence.

Think about the number of companies that have been created to make, or heavily specialize in Arduino clones and accessories without having to pay Arduino a cent because the designs were intentionally open-sourced. It doesn't sound like a naked cash grab to me.

I don't doubt the boards could've been sold cheaper, but they clearly were doing something right given how much it changed the hobbyist landscape