We just discussed – you do not return lost money to a non-Jewish person, at least in the case where non-Jews are abusive of us. This does not mean you should steal from him, you should just not do him a favor that strengthens him. In the modern world, we are free to do business with whomever we want and patronizing someone’s business is doing them a favor as this strengthen him – not just by the profit he is earning, but he can pay his own workers, and develop stronger industries.
We did not lose much from boycotting Cuba, there are other places where you can travel. We should not do business with other dictators also. Instead, buy from countries that are standing up to them – Israel, of course, Taiwan, Ukraine, etc.