Another reply mentioned how the same questions can be asked of people joining the US military. And I'll add the examples of buying clothing made in sweatshops, hi-tech devices made in sweatshops, blood diamonds, bottled water, and even factory-farmed meat if your concern for suffering extends beyond human suffering.
It's easy to ignore the consequences of your choices when they do not directly impact you or the people you know and care about. I am not crying 'hypocrisy!' here--I take part in these systems too--only pointing to things that many of us do that can be viewed with equal abhorrence by those who pay attention to them. And I think that is the answer to your question: it's all in what you pay attention to.
It's easy to ignore the consequences of your choices when they do not directly impact you or the people you know and care about. I am not crying 'hypocrisy!' here--I take part in these systems too--only pointing to things that many of us do that can be viewed with equal abhorrence by those who pay attention to them. And I think that is the answer to your question: it's all in what you pay attention to.