As in any other case, to persuade another person is to assert a claim. It doesn’t matter that you already have done the requisite learning to understand what you’re certain is the baseline set of facts. What matters is you want to change someone else’s beliefs.

As an example:

It would be preposterous for me to say “I am certain that biological sex is a spectrum, and binary sex is a simplification useful as a tool for some applications but inadequate for others” and just expect anyone who doesn’t know that to crack open a book or start googling my hypothesis credulously. Even though I’m certain it’s true.

I understand that while there’s sound scientific basis for the claim, it’s not a shared understanding of reality.

I also understand that it’s a claim that may be questioned, even though I’m certain it’s correct, and it’s my choice whether to give it more weight when challenged (attempt to persuade someone who doesn’t accept the claim l) or to carry on certain I’m right. But if I take the latter path, I have to accept that it’s really very unlikely the other party will learn what I’ve learned, unless they become curious and open to the possibility.

In other words, you can be right until the end of time and it wouldn’t ever matter to some people unless you give them a reason to want to be right too.