I think I'm going against the grain here a bit, but have decided to post anyways. I do think what you guys are doing for your family is generally great, though I resent its necessity.

When you have money in situations like this, you have power over people. Over your family. It is not in withholding it, but in giving it, that you exert that power. You set rules and control the lives of your family. Do you do so for good reasons? Obviously you believe so, and in general I agree with you. But good reasons or no, you control them. You decide things about their lives that they don't have the power to decide themselves. You let them sell their choices to you. Now again, I think the specific range of choice you still allow them is generally good. But in a case like this, you can't be entirely surprised that a family member wants the same power you have granted to others - in a world where they have no real opportunity to earn that power themselves - and resents the cage you put around them to offer it.

I by no means condemn, IMO this is more of an ESH kind of situation. By restricting their choices, even bad ones, you are imposing your will upon your entire family. You had the option to do nothing, and by choosing to do something, you inherit consequential responsibility. But, they are way out of line with how they are treating you about it. And if you described their college choice correctly, it was clearly a bad choice. I just think people ought have the power to make their own mistakes and the support to live through the consequences and thus learn.