Most, I would wager, weren’t motivated to do it for Reddit. They were motivated to do it for their communities that happened to be on the site.
Moderation— particularly volunteer based moderation— tends to be about the bonds moderators have and develop with the users they interact with every day. Admins are a mixed bag: some of them may have sympathy towards the mods, but ultimately their livelihood is tied to the company line.
A lot of the internet is built on free labor. A lot of that we have been willing to let slide. That willingness ends when the quantum of respect doesn’t get paid for that labor. I don’t know how someone continues moderating on Reddit at this point; barring a big turnaround(and possibly the ouster of current management), it feels like the move should be to migrate their communities elsewhere.
It’s not like C-level folks aren’t cashing in well before their companies are profitable. They put on executive clothes and live executive lifestyles, either because it’s what they want or because it’s part of the theatre put on for investors.
I feel confident in the assumption that most users wouldn’t begrudge a company a modest profit off of the content they produce uncompensated on their sites. But it’s an unwritten social contract, and therefore ripe for abuse.
Some of it is born of users not realizing the value of what they give to the corporations— their data for mining, their engagement for attracting and maintaining even more users to the site. Some of it is born of the explicit contracts being written solely by one side(the execs).