“I’ll have to assume you meant the ‘not a religion’ part.”
I’ll then assume when you said Buddhism is not a myth then you meant the teachings of Buddhism are a true religion, or at least a true philosophy/way of life.
Now Buddha himself might be a myth; I've no way of knowing.
I explained (quite well I thought) that SOME consider Buddhism to be a religion (true or not is in the eye of the beholder) to me it is NOT a 'religion', for it has no GOD.