what in the world was this fish thinking?”
That's just it, they don't think. Predator fish are hard wired to the tune of millions of years. They probably can't help themselves when the chance of a meal comes along. They just go for it, and, if it's even possible, think about it after as they're choking to death and it's too late!! Lol.
Many years ago during a fishing trip I was in the shallows returning a decent sized bream to the water. In the blink of an eye a small jack pike, around 14" long launched itself at the bream, which I still had hold of, it missed, and took three fingers of my right hand in its mouth instead!!
It wouldn't let go and made a mess of two of my fingers. That fish didn't die due to choking....it died due to me giving it a right wallop....and tasted wonderful when I ate it later.