In my own head the Borg aren't the result of a single catastrophic event, but the result of a delta quadrant race pushing towards a singularity and gradually giving up more and more responsibility and the running of lives and society to a universal computer network.
I definitely agree with @Newman's Lovechild proposed origin of the Borg being an ordinary, nobody race that spiraled out of control in their effort to improve and unify. It not only fits with some hints we had in Voyager, but it also makes them much more horrifying with the slippery slope implications.
I always headcanoned the Borg as having started out as a regular race, but one that was already rather collectivized and devoid of personality to begin with. Essentially a race that speedran from monkeys with sticks to warp drive in a fraction of the time it takes a regular race to do so.
Some of this is my own personal bias, which I will be the first to admit is kind of extreme. The idea that the Borg ever once had art, games, literature, or anything of the things we generally associate with culture
completely destroys their menace for me. However, think about it for a moment; if the PreBorg really valued things like art and cultural heritage, wouldn't they look for and assimilate that from other species as well? The fact that they apparently hold no regard for expression at all suggests to me that they never learned the value of it in the first place.
I know a race that never invented art or culture but eventually made it to cybernetics and spaceships sounds kind of silly, like how HG Wells stated the Martians never invented the wheel despite being more advanced than humanity, but its hardly the silliest thing that's been suggested in Trek.
Reckless my ass. He is as professionaly as Picard, but isn't afraid to get his hands dirty.
He was definitely reckless on some occasions, such as the time he gassed a Maquis colony just to play tit for tat with them for poisoning a Cardassian colony. The colonists all escape before the toxic shit spreads, but I have no idea how considering he gave them like minutes of warning before opening fire.
The entirety of In The Pale Moonlight is also reckless as fuck. He even admits it in his log, and states plainly that if he fucked up at all in this plan, it could actually cause the Romulans to side with the Dominion which would pretty much be game over for the Alpha Quadrant. Its a great episode, and one of the reasons why Sisko is fucking awesome, but even the man himself said the idea was an insane risk and he got damn lucky that Garak had a backup plan.
