In reality you could host the entire thing for well under $50k/year in hardware and storage if someone else is providing a free CDN. Their costs could be incredibly low.
But just like Wikipedia I see them very likely very quickly becoming a money hole that pretends to barely be kept afloat from donations. All when in reality whats actually happening is that its a ridiculous number of rent seekers managed to ride the coattails of being the defacto preprint server for AI papers to land themselves cushy Jobs at a place that spends 90+% of their money on flights and hotels and wages for their staff.
I'm already expecting their financial reports to look ridiculously headcount heavy with Personnel Expenses, Meetings and Travel blowing up. As well as the classic Wikipedia style we spend a ton of money in unclear costs [1].
Whats already sad is they stopped having a real broken down report that used to actually showed things. Like look at this beautiful screenshot of a excel sheet. Imagine if Wikipedia produced anything this clear. [2]
[0] https://blog.arxiv.org/2023/12/18/faster-arxiv-with-fastly/
[1] https://info.arxiv.org/about/reports/FY26_Budget_Public.pdf
[2] https://info.arxiv.org/about/reports/2020_arXiv_Budget.pdf
This just isn't true. arXiv nowadays has to deal with major moderation demands due to the influx of absolute drivel, spam, and slop that non-academics and less-than-quality academics have been uploading to the site.
Moderation for arXiv isn't perfect or comprehensive but they put so much work into trying to keep the worst of the content off their site. At this point while they aren't doing full blown peer review, they are putting a lot of work into providing first pass moderation that ensures the content in their academic categories is of at least some level of respectable academic quality.
First pass sanity checks are also a lot less fun than proper peer review so paying moderators to do it is probably safer in the long run or else you end up with cliques of moderators who only keep moderating out of spite/personal vendettas against certain groups or fields.
Non-profits aren't maximizing stock value, but they do need to optimize for stakeholder value - you want to maximize the amount of money being donated in and you want to make the most of the donations you receive, both to advance the primary mission of the non-profit and to instill confidence in donors. This demands competent leadership. The idea that just because something is not being done for profit means the value of the person's contributions is worth less is absurd. So long as the CEO provides more than $300k of value by leading the organization, which might include access to their personal connections, then the salary is sensible.