Prediction: Arxiv has no need of this money, as it has no need of upgrades. This money will exclusively attract salesman, all of whom will offer to make arxiv worse, for money. One of them might succeed
I concur. Seriously it's job is to act as a repository of PDF files. It does that it does that well. It doesn't not need a fancy new frontend that changes again in 18 months because "circles are in" it doesn't need to move to a "distributed load balanced fault tolerant web scale platform solution" (that costs about 2x in maintenance and engineering time as it currently does).
It doesn't need to do anything of these things. It needs to serve documents and thats it. If there are problems with load they can always throw it behind a CDN since all of their contentt is largely static it fits nicely into the use case CDNs were developed to solve.
