My self-loathing prevents future versions from allowing others to defeat me. Only *I* can defeat me.

Nothing prepares you for an evil future version of yourself. It's an Enemy Mine scenario at best with time-traveling.

But I'm a skeptical guy by nature, so a good-future-me would play their cards openly ("I'm going to kill 15 people to avert World War III/The Great Plague", "We have to steal and destroy this technological research to stop the robot A.I. uprising"), while a bad-future-me would have to play an elaborate chess game to make everything they want appear more constructive than destructive, while also psychologically manipulating me with speeches and actions.

And knowing that as myself now, bad-future-me's would change their style accordingly, so...

Let's just say teaming-up with myself would be a last resort for all parties involved.