I’ve said this before, but it’s worth saying again: there’s very little point in trying to learn something computer-related if you’re not going to use it in the very near future. If you’re not using Kubernetes or ZooKeeper, and if you don’t have a specific academic interest in distributed algorithm implementations, learning what distributed algorithms they implement serves very little purpose.
You have to understand that Kubernetes and ZooKeeper are both insanely complex systems. If you don’t have extensive knowledge of the concepts they use, and you don’t actually use them in practice, you have no hope of understanding them in any meaningful way.
You’re asking me to educate you, but you haven’t yet demonstrated any actual willingness to educate yourself. If you can’t give even the beginning of an answer to questions regarding their purposes, I’m afraid I’m not interested in helping you.
I understand both of your points but have no reconciliation to offer between them.
I'd have to side with Stephen on this though. There is plenty of free information on Z & K and even in the few minutes since entering this chat I've read about both. He even offered you alternative sources, one of which is free. Even the documentation. To keep asking is near trolling.