And the series starts out with O'Neill still not fully past that tragedy, but as time passes he moves on more and more.
Although I didn't like how much RDA took it to the point of caricature in later seasons, taking Jack from someone who had little patience for intellectuals to someone who played dumb sometimes but was an amateur astronomer to someone who really was pretty dense and had no astronomical knowledge to speak of.
I chalk it up to the progressive brain damage he suffered over the course of the series.
1) devolving in "The Broca Divide"
2) being exposed to mind-altering substances in "Hathor", "Seth", "The Devil You Know", AND "Paradise Lost"
3) being exposed to mind-altering devices
in "The Fifth Race", "Holiday", "Legacy", "Upgrades", "Beneath the Surface", "The Light", AND "The Lost City" (and having his brain tapped into in "Tin Man" and "Foothold")
4) being put into suspended animation in "Out Of Mind", "The Lost City", and "The Gamekeeper" (along with being trapped in virtual reality)
5) getting invaded with nanotech in "Brief Candle" AND "Message in a Bottle"
6) suffering hypothermia in "Solitudes" and "Tangent", as well as hypoxia in the latter
7) suffering from a deadly virus in "Frozen"
and 8) being subject to multiple sarcophagus sessions in "Abyss" (as well as being temporarily taken over by a symbiote)
it's no wonder he wound up a drooling idiot.
That's why he was promoted to general.