If all content aside from levelling your main to max level, gearing it in the best gear in every slot, and taking part in Extremes, Savage raids and any Ultimates for the current expansion, isn't End-game content - clearly you haven't reached End-game until you've cleared all that other content. It's still to be done, therefore you're not at the end of the game.

In contrast, if you can reach End-game by levelling your main to max level and gearing it fully, anything you do after that point is End-game content, even if it's chocobo racing.

What you are really saying, OP, is that there is nothing you personally enjoy doing once you have reached max level, geared, and completed Savage. Which is a very different thing from lack of endgame content