Dyscalculia and excuse

When I told some people that I have severe Dyscalculia and that I don't know how to do most basic math and that I don't know how to do Calculus even, some of them think that I am using that as an excuse for not being good at math. I had failed math most of my school years and it's not just me being only bad at math, and I still don't know how to do most basic math as a 22 year old and that is not normal. I tried explaining that to them, but they didn't listen.

Some people think that everyone can learn math, the question is if they understand that when you reach a limit before Dyscalculia manifests.