I don't like seeing death myself so OP nailed it for me.
Just one slip is the second thing. A very unforgiving hobby. A bad math day calculating a dosage and stuff dies before you can fix it. Too short an acclimation time. Putting off cleaning something a bit to long. Wrong tankmate for a new fish.
Just one slip and things die.
I am not that good anymore so I am extra careful these days.
definitely the chemistry and balance necessary to maintain a beautiful reef. the cost doesn’t outweigh the end result…can always make some money back by fragging