Not annoying at all. You wrote:

>I am an undergraduate student double majoring in computer science and mathematics. Over the last few years I've noticed that companies like Blizzard and Bethesda welcome applications from Math or CS majors...

Yes. That double major is the recommended background for 3D graphics programming (which is hugely important in video games).

> I'm able to pursue a masters in either, specializing in cyber security or theoretical mathematics, but am wondering if I'd have a better quality of life working in the gaming industry.

You're comparing QoL in grad school versus the game industry? First off, one will pay you a lot better than the other. If you really want to go to grad school, then go for it, and study whatever interests you the most.

> how marketable is someone with two bachelors in CS/Math to a competitive game company given they have little to no experience in game dev (do have experience in full stack dev for ~2 years going on 3-4).

The double degree is highly attractive. Lack of any game portfolio whatsoever cancels that out. If "full stack" means familiarity with both front end and back end, that is a plus. So you're at +1 instead of 0 (or 2, or 3).

> Would receiving a masters in either increase my marketability to such companies

No. Read my article on A Matter of Degree.

> if so, which area would be more appealing?

Please don't plan your life based on what you think others expect of you. Go for the area that's "more appealing" to YOU.

> I like the idea of the quality of life provided by some of these game companies

You lost me. Game industry QoL is infamous.

> I just don't want to graduate being overly qualified yet financially barely getting by....

Then that should tell you not to go for the graduate degree just now. You can pursue that avenue later in life, if you wish.