What are pros and cons of submitting a PhD thesis to ProQuest? Many people published their PhD theses in ProQuest, and it looks cool. The thesis is indexed by ACM as a book, so you can list them in the publication section in your CV. I wonder if there is any disadvantage if I do the same?

To be honest, I really doubt that anyone will ever read my thesis. But I have spent 3 (extremely painful) months to complete it. So I want to decorate it a little bit.

My university has a public repository for PhD theses, it is googlable, but not indexed. I already put my thesis in ArXiv.
I don't see any advantage to posting your thesis to ProQuest, but I don't see any real disadvantage either.

Since your thesis is already on ArXiv, it's already permanently (and freely!) available. So I don't see any advantage to also making your thesis available through a more painful interface that requires your intended audience to give other people money. Presumably the results in your thesis will also be (or have already been) published in other indexed publication venues, so even having your thesis indexed by ACM isn't a clear advantage.

You can list your thesis in your dissertation even if you don't submit it to ProQuest. In fact, you must list your thesis in your CV, even if you don't submit it to ProQuest.

(JeffE's answer.)