There's literally thousands of things you can do. There's a ton of lore to look into, there's like a billion quests in each expansion, there's relic weapons, Eureka, and other content like that. There's beating every dungeon at every difficulty level and I guess if you don't like savage / ultimate for whatever reason (I don't like dungeons but like savage / ultimate) so we all have our different tastes, then you can always play the glam / housing game. Collecting all the emotes / mounts / orchestreons and other things that are collector's pieces is another thing you can do. PvP which I doubt is your thing is something else you can get in. There's Heaven on High / PotD, New Game+, beast tribes, crafting and gathering especially with the new 5.21 content with ishgard restoration and ocean fishing.

I don't know many people who have completed everything. I'm approaching year 2 and have completed almost everything I listed except I haven't finished all Stormblood and Shadowbirnger quests yet and am missing a few new mounts, minions and orchestreons. There's so much to do. I know you are mentioning main-class progression but maybe you should consider not just playing a fighting class since that is only one part of the game? You should get into savage content, it isn't that hard and you don't need to use discord. It'll help for pugging but you don't have to.