That's one of the reasons why I love King K. Rool as a character so much. His plans in each main series Rareware game got progressively more insane.
• In DKC1, he took the banana hoard in order to gain the Kong's attention, as the Kremlings attempted to take over their island. My headcannon of their goal was to starve the Kongs enough in order to get rid of them, meaning they could take over the island easily. The Kremlings easily underestimated Donkey Kong and Diddy Kong though.
• In DKC2, King K. Rool now saw Donkey Kong as a threat, so he successfully kidnapped and tortured him throughout the game as the Kremlings invaded the island once again. He also used Donkey Kong's kidnapping to blackmail Diddy for the banana hoard, knowing how much the bananas meant to Donkey Kong in the first game.
• In DKC3, King K. Rool sees both Donkey Kong and Diddy Kong as threats, kidnapping them and utilizing them both as living batteries. On top of that, Dixie Kong and Kiddy Kong didn't even know they were kidnapped; they thought they just went missing, and went to look for them without yet learning King K. Rool's involvement. They seemed to be aware of KAOS however.
• By the time DK64 happened, King K. Rool was losing it. He felt that this could have been his last chance of taking over DK Isle for himself. After his attempts of learning from his mistakes didn't work out, he realizes that he needed to go all out with nothing held back. King K. Rool's main plan was to fire a laser at DK Isle and completely obliterate it. Once it didn't work out and he needed his laser repaired, he kidnapped four of the Kongs and stole Donkey Kong's banana hoard once again. This would ensure that Donkey Kong would starve, not have anyone to help him, and let him realize the reality where his island would be nuked soon. Of course, Donkey Kong is persistent and stopped King K. Rool anyway.
After DK64, I personally felt like no matter what King K. Rool did, he felt like he couldn't win. This could be due to various factors, like the resilience of the Kongs, the incompetence of his minions, or just the general feeling of hopelessness. I think the way Rare portrayed King K. Rool's descent into madness throughout the Country trilogy and DK64 is really great, as it's hard to find villains that recognize where they went wrong, how they could improve, and when to know to quit.
I definitely agree that DK64 was King K. Rool's last big hurrah, as his plots in the DK Jungle Climber games felt much more Bowser-esque, in the sense that he just wanted to take Donkey Kong's bananas because he's an evil guy and does evil things. Rareware's portrayal of King K. Rool felt like so much more than that to me, a great villain who always strives for greater things, and had to eventually realize that everything was working against him at all costs. King K. Rool will always be my favorite Nintendo villain because of that; he's comical and insane, yet is self-aware and flawed. King K. Rool always did the absolute best he could, yet he left when he was still bested by his competition regardless of what he did. I have a lot of respect for that.