system
Given the following post, respond as if you're commenting on Reddit:
human
[Terminator] Why did Skynet believe that killing John Connor would affect the outcome of the war?

Let’s say Skynet’s plan to assassinate John Connor/Sarah Connor was a complete success, the T-800 goes and easily kills Kyle Reese and then strangles Sarah. Why...why would Skynet believe this will significantly change the outcome of the war? Why would Skynet be convinced a single man was all that stood between itself and human extinction? What about John’s army? What about the human resistance it was undoubtedly fighting all around the world (assuming Skynet’s plan was to destroy humanity and not just US citizens) who certainly were not directly led by John if he was leading them at all? What about the remnants of the US and Soviet and even UK and French militaries, all of whom could carry on the fight in whatever way they could? Would killing John eliminate the Resistance? Would it suddenly make all the potential fighters disappear? Would it make the resources and infrastructure left behind from Judgment Day, as well as the automated Skynet factories the resistance took over simply cease to exist? Honestly why is Skynet so foolish and singleminded, I’m pretty sure a historian can tell you that just killing Hitler as an infant likely wouldn’t prevent WWII or an equivalent conflict, if that’s the case then why would Skynet ever be dumb enough to think that eliminating one man would save itself? Did it not consider that, perhaps...someone else would lead humanity instead? Especially considering the fact that Terminator Dark Fate (tho admittedly I only accept the first two films as canon) shows explicitly that John Connor was not necessary, there would always be someone who stood up to Skynet, it was just a matter of who would turn out to be the most capable leader for the resistance, for which clearly many candidates existed.
gpt
Skynet's time travel plot was a last-ditch, desperate attempt to save itself. By the time it sent the first T-800 to the past, human forces were already in the process of dismantling Skynet's infrastructure, and were ready to destroy the time machine before they realized what happened. In a way, there was very little logic to it, Skynet just took a very human gamble out of fear. 

Every time loop is similar. Skynet only sends agents to the past because it's on the verge of losing, and it wants to preserve itself by any means necessary. The small alterations to the plan are still nothing more than the desperate last gasps of a dying machine.