Why I care about:
Religion: Because it is a topic that a lot of people care about. Personally, you can believe whatever the hell you want to believe, I really don't give a damn. But the instant you start telling me what to believe (or what not to believe) in, and assert what is right and what is wrong, then I will stand up for what I think is right and wrong, and do everything in my power, to destroy your opinion. But if you just keep it to yourself, then you can continue to live in your fantasy =)
Ideals: They are what make me me, and when they are called into question, I will say why my ideals are right. If I don't stand up for my ideals, then why do I exist?
Favorite Ice cream: It tastes good, and my taste buds are kind of important to me.
Anything: Because caring about something shows that you are a rational human being with rational concerns about things. The opposite about caring for anything, would be caring for nothing, or caring for everything. Caring for nothing leads to death, so that is obviously stupid. Caring for everything is too much work. Of course I have an opinion about everything ever, I am a guy who thinks way too much about everything. But I don't care about most things because they don't affect me, or are beneath my notice.
I hope that satisfies your question.
I am willing to admit when I am wrong, but when someone says that I am wrong without support, somebody gonna get a hurt real bad...