Wellll, there's not exactly that much incentive to have alts on your main account. The vast majority of your gold income comes from your labor points and your weekly epona bag, and those are account/server shared. You can use alts to do the content that gives you tradable upgrade mats, BUT that requires those alts to be on the same tier of gear as your main, so you'll have to spend gold to upgrade their gear too, which kinda defeats the purpose. (A lot of shit you get is character bound, another issue I have with the game) I do use the alts on my main account for silver farming. There's a quick daily that gives silver, how much is based on your gear score. My lower (400s) GS characters get like 5k, my main get 18.7k. Dailies have the same double bonus mechanic as guardian raids. So, on most of my alts I only do that daily, and get 10k to 37k each per day. They like to give you boxes of silver as login rewards (in RU currently it's like 300k to 500k) which you'd think is a lot, but it isn't. Upgrading your gear costs silver as well as gold, and things like rerolling gems costs silver too. I can easily spend a couple million in a day.
There's no real reason to race to upgrade your gear (engravings are more important anyway). And I avoid the RNG upgrade BS as much as possible by taking breaks. As I mentioned previously, the game gives you catchup items every few months, 100% upgrade chance (and 3 levels at a time instead of 1) and 75% reduced gold cost.
The gold earning isn't even my number one issue with the game, it's just really annoying. My main issue is that, since pretty much all endgame activities are related to it, and therefore limited, you actually can't play the game once you've hit your limits for the day/week. Except for arena pvp.
Guardian raids. Can enter as many times as you want, but only get rewards twice per day.
Chaos dungeon. Enter twice per day.
Test paths (boss rush) and Cube. Require tickets you get as drops in Chaos dungeon.
The rest is once a week dungeons and raids.
There's other shit to do, much of what you need to do if you want all your skill points. But, I don't really consider it "play". It's mostly going to an island, getting a quest, and then running around the world talking to people (ie skipping boring dialogue) or going to some other island that only appears during certain times of the day, or certain days and killing shit for rng drops. That's for "Island Hearts". I need 20 for my skill point pot, after playing since launch I have 11. And they keep adding currency like this, There's Giant Hearts, Orpheus Star, etc etc.
The core endgame loop is basically done after a couple hours per day. This is an area, if you like more than 1 class, where alts can help a bit.
Oh, I almost forgot about the Affinity system. This is how you get certain rewards from story NPCs who are now your friends. You get 5 emotes and 5 songs per day. Playing songs and doing emotes to these NPCs give you Affinity with them. At certain levels of Affinity they will offer you a quest, but in order to accept it you need to have reached certain numbers in these secondary stats (Bravery, Intellect, Kindness and Charm). That's another grind. If you don't have the required stats, you cannot continue to gain affinity with them. Also, while you'll get some songs and emotes through normal leveling, getting many of them will require jumping through more hoops. You don't always need to max affinity with an NPC to get the reward you want, but on the ones you do it can take months. Through events, quests and login rewards you'll get gifts that give a lot of affinity. Save these for the important ones. Runes, skill pots, secondary stat increases etc.
TLDR: Game has a lot of time wasters, but doesn't like to let you actually play the game, unless you PVP in the arena.
