Exactly. While it may be an acceptable theory on how matter and energy was disbursed and the cosmos was set in motion, it does not explain...or even come close to explaining...where all the matter and energy that was compressed into an infinitesimal point came from in the first place.
Let them explain what happened or was happening 1 second...or ten or twenty seconds BEFORE their big bang.
“Start here. Magic Happens. Universe!”
Viola!