Are there truly people who believe gay marriage threatens straight marriage?

They have conviction, blind faith that what they say is true. But they cannot support it, that kind of critical though is beyond their capabilities. So, they just act out of juvenile spite and self-justification, because that's all they've got. No facts, no history, no logic, no reality.

Of course, or else this whole say progression for same sex marriage would have been long accepted, over and done with.

It's quite depressing, be it more people do accept same sex marriage now, that those whom accept it are more/still of a minority, compare to the rest of the world. Regardless though, progress is still progress. It just shows that we still have much growing up and learning/understanding to do.

Yes, there are some ignorant people who believe this. Kind of makes you lose faith in humanity, doesn't it?

i mean... yeah. there are a lot of incredibly stupid people who believe that gay marriage somehow devalues their own hetero marriage. it makes no sense, but yes these people really do exist. just don't try too hard to force that view through logical reasoning because you'll just be frustrated.

"Conservatives" are damaged, angry, self-righteous people who think they're protecting society by never allowing it to change.

They tend to imagine themselves to be Right...and if you're Right, then what you think is Right... and anything else is Wrong. "Conservatives" tend to believe their own bullsh*t - which is what put us into Iraq.