The odds just seem so against doing much good in that specific kind of situation. Other situations, definitely, I can see and have known about how they save the day.
Incidentally that SOB and his crazy wife left behind not just a terrible trail of grief and tears but an orphaned 6-month-old child. There will be terrible cost to society yet to be paid.
The child will probably qualify for Social Security death benefits because the father was gainfully employed for 5 or more years (about). The critical victims and even the ones not so badly injured; their lives have been altered in a few seconds. Some will no doubt need disability for the rest of their lives if there is any left to be had.
I think it’s one of those things like you are just standing there and the guy walks in and you drop him. If it’s at a distance your pistol is useless so you take cover as best you can I suppose. Horrible either way.