I would not & am not mocking sincere Christians.
But I don’t put any stock in people making serious chronological predictions of this nature.
I was raised Christian and remain so, but I also remember a verse about who no one knows when He will return.
I knew an engineer on the Trident Missile Program who claimed to know exactly when the end of the world would be and showed me on the white board in his office how it would be sometime in 2001.
He will come again. In his own blessed time. We should worry more about living as He would have us live, instead of worrying about exactly when He will come.