As a former mod, in my experience it was more having a place to engage a community, and helping that community grow and improve. Reddit being a million dollar company when I started and a billion dollar company when I left didn't really factor in. If you have a site split up into a million little communities, you need moderators that can have intimate knowledge of each community they oversee, and that's unreasonable for a company of any size to do in house. Otherwise you have Facebook style moderation where it's just plain dreadful no matter where you are.

Additionally, it really matters what sized sub you modded.

I modded mostly smaller subs, one big one for a while, and a default for 2 weeks. I put a lot of effort into the smaller subs, especially when it was just a few people whose usernames I recognized posting. I had little jokes hidden around, some cool CSS stuff, and some automated tasks. It was an enjoyable way to spend a couple hours a week. I didn't mind it.

The big sub I was on mostly through mutuals. I was known to be pretty decent with automod scripting, so I got brought in to deal with never ending spam. I would update the automod and check queue every couple days, no biggie. Then the rest of the mods all drifted offline, leaving me alone to either let the sun die or to try and maintain the damned thing.

I maintained it near single handedly for like 2 years. It was mostly adding more and more to automod, but a lot was manual approvals and deletions. It sucked and sapped all the fun out of an activity I used to enjoy. Wasn't the worst, but I wouldn't have joined in the first place had I known why would happen.

Default subs are a different beast entirely. They don't even use automod half the time. All of them have custom bots that link either a slack or discord, and everything is run externally through there. I decided to dip when I asked how tf all their tools worked and got refered to almost a damn knowledge base. That truly seemed awful and like it needed to be done by dedicated and paid employees.

Anyways, this comment spiraled, so sorry about that.