but it seems to me that there are one HELL of a lot of privileges reserved for specific classes of people,

Then, consider that civil marriage is one of them. Name some others.

including the entire arc of "equal opportunity" preferences on the basis of race or gender.

Oxymoron time . . . equal protection is not "equal opportunity" -- thnk desegregaton, for instance. There are no preferences involved in allowing persons of different races to use the same public bathrooms, drinking fountains, restaurants, or lodging.

But I suspect you really mean "affirmative action" anyway. Let me know if I'm wrong, but the whine sounds familiar. This next bit of floundering for straws seems to stretch that way:

If I were to mark "Hispanic" on an application and get into college on that basis, how could I be faulted for this?

Probably for filing a fraudulent application, unless you really are Hispanic. That's a felony, isn't it? And where, pray tell -- even in the liberal paradise of Calyforniya -- can you gain admission to college solely on basis of race or ethnicity?

Am I not entitled to any state benefit that is given to any other class of people?

You may be, if you can prove you've been denied such. You certainly have the right to sue, as did the plaintiffs in the case under discussion.

You could have been a lawyer, Tom -- or an ambulance chaser, anyway. You've gotten an awful lot of practice at misdirection and obfuscation here in the Zone.