I receive a lot of criticism regarding Zoro wanting and having the ability to teach Haki to other people, but I think people don't realize one thing.
1) Teaching someone Haki and the fact that the person has mastered Haki are two different things : Even if he teaches Haki to someone, that person will only have their own determination and talent to master it. Megumi, for example (the one from the manga, not the fanfiction), simply doesn't have the mindset needed to perform well with his haki and Ijichi simply doesn't have the talent to master it.
2) If we disregard ryo, armament haki is heavily dependent on a person's physical strength Although JJK characters can strengthen themselves with this, none are more than the building building level with just normal attacks enhanced by cursed energy, So don't expect Yuji, or anyone else for that matter, to be able to perform Galaxy Impacts.
4) Regarding Conqueror's Haki, I currently only know of 5 characters who, in my opinion, definitely possess it: Gojo, Sukuna Maki (yes Maki), Kenjaku, and Hakari. For Gojo, Haki requires death matches that push you to the limits of your determination in order to evolve, and considering that the only ones who succeeded in the manga are Toji and Sukuna, I don't see He has many opportunities to grow. For Sukuna and Kenjaku, it's simply impossible for him to decide to teach them. I already explained in a comment on chapter 1 or 2 why Sukuna wouldn't be able to learn it even if Yuji did, I'm too lazy to explain again, so just go read the comment yourself. Therefore, only two candidates remain to master Conqueror's Haki, knowing that some never reach the conqueror's haki coating
4) THE FATE OF THE WORLD IS LITERALLY AT STAKE, AND YOU WANT HIM TO KEEP HIS POWERS TO HIMSELF INSTEAD TEACH THEM FOR SAVE PEOPLE LIFE ? BUT YOU'VE LOST YOUR MIND.
So please don't come and harp on about in later chapters that he shouldn't teach Haki to others; if you're not happy, just stop reading.
If you are looking for a selfish protagonist who has nothing to gain, you are in the wrong place.