Is Satoshi Nakamoto really the founder of bitcoin?
Yes.
Then why he did not show in public? What do you think the reason maybe?
Why would he? He would most likely be in life-threatening danger if he did.
He might be a billionaire by now if he showed his true identity in public.
He doesn't have to show anything to the public. Anyhow, Bitcoin is not based on trust, nor any kind of authority. Who invented it does not matter at this point, nor does any know who Satoshi is.