Because we observe the contingent in the universe.
Not the same thing (fallacy of composition).
Necessity arises from contingency. If the contents of the universe is contingent then there must be something about the universe which is necessary if the universe is contingent then the universe is contingent on something which must necessarily exist.
Non-sequitur. Even if the universe is contingent on something, that doesn't imply that anything exists necessarily, whatever the universe might be contingent on, could, in turn, be contingent on something else.
You haven't even tried to explain how something could not fail to exist; how that is even logically possible.
Contingency without necessity is nonsense...
You haven't shown that, just asserted it. Even if you assume that there is some end to the chain of contingency, then you haven't shown that it must be something necessary, in the sense that it couldn't have failed to exist, nor how that is logically possible. You keep wittering about PSR but you've totally failed to make the case that anything could even be imagined that could be its own sufficient reason.
So I haven't given sufficient reason for sufficient reason then.
No, try reading what was said. You are effectively claiming that something exists that couldn't have failed to exist and so must be its own sufficient reason. You have totally failed to explain how that is even imaginable, let alone real.
And this idiotic mantra of yours is also an
equivocation fallacy.
And that is now a problem because you seemed to believe that the universe just is with no sufficient reason.
At least we can imagine a cycle of contingency, an infinite causal chain of contingency, or something that 'just is'. Something that is its own reason for existing, on the other hand, seems about as credible as a square circle, so far. You have given not the first hint of a reason as to how that could possibly work.