The horns were also to push individuals of the same species, but to attack? nope.

They could most certainly pierce skin

^^^Coming from someone who has touched a Triceratops horn, try me.

But the trike was not defenseless, it had a very powerful bite

Its bite force hasn't even been estimated.

Ye but due to it's big head and beak their bite was probably very strong

And the protoceratops, a relative of the trike, had a strong bite

That's just speculation you made up, you can't say that's fact

Strong bite and horns. The latter was probably much more useful.