In Star Trek II: The Wrath Of Khan, why didn't Khan just wait outside the Mutara-class Nebula until Enterprise came out and then just finish them off? Considering the fact that he had a genetically far superior intellect, one would think he wouldn't be so clumsy in thinking like how he did. Didn't he know that it was a suicide run?
Khan was obsessed with defeating Kirk. He didn't just want to win, he wanted to beat him. In "Space Seed" Kirk bested Khan in physical combat and sent him into exile, a deeply humiliating reversal for a man whose identity rested heavily on his supposed innate superiority. Defeating Kirk was personal and all consuming for Khan, and he was willing to risk anything to achieve this victory. If there was any doubt of Khan's obsession, the Ahab quotes from Moby Dick sprinkled through the script should banish them. Khan said this when asked to consider taking Reliant and declaring victory:
KHAN: He tasks me. He tasks me and I shall have him. I'll chase him round the moons of Nibia and round the Antares maelstrom and round perdition's flames before I give him up.
Khan's obsession combined with his repeated mistaking of raw intellect for experience ensured that he would stumble into the traps laid by an experienced and cunning adversary.
Slightly speculative, but he probably thought following Enterprise was his best chance to kill Admiral Kirk. He had no way to know what repairs Mr Scott could make if Reliant waited outside, so he would be concerned that Enterprise could eventually warp away. Additional Federation ships might also show up to find out what was going on in the area.
In any case, it wasn't a suicide run, as Spock himself says.
Sauce for the goose, Mr Saavik. The odds will be even.
Kahn was furious at Kirk, he had to confront Kirk and beat him because he had escaped his attempts at revenge three times:
- crippling the Reliant with the hack,
- surviving Captain Tyrel's assasination attempt, and
- escaping the Regula test site so fast
Kirk also knew how to bully Khan into rage, and managed to cancel each advantage Khan had, shields and sensors, get into the nebula, higher intellect, get him furious.
Khan couldn't "wait outside" the Mutara Nebula. That indicates, as Spock would say, "two-dimensional thinking." The Nebula wasn't a building with one door. If Reliant stopped pursuing, the Enterprise could escape in any direction it liked, even before making any repairs. Khan did consider giving Enterprise up, and allowed Joachim to break off the pursuit. But then Kirk goaded Khan. Khan may have been smart, but not so smart he didn't let his crazy high emotions get the better of him.
One small but BIG 3 letter word --- Ego
Kahn's ego was his downfall that allowed Kirk to manipulate.