It's worth noting that this is a trend, not a black and white rule. Some people _do_ plan it ahead of time, in some form or another.
E.g. my uncle specifically bought rope and carabiners prior to his suicide, and, apparently, had googled instructions on how to tie a noose several days ahead of the actual thing.
I imagine it comes in waves. And even if one wave just pushes someone to the point that buys ammo, the next has to push it only to load the gun, and the final one just has to push it to pull the trigger a little harder. :/
E.g. my uncle specifically bought rope and carabiners prior to his suicide, and, apparently, had googled instructions on how to tie a noose several days ahead of the actual thing.