Such cards are useless for mining, least of all in California where electricity isn't exactly cheap.
My video card has completely paid for itself almost double what I initially paid for it ($2K in cash from a seller on craigslist, back in January).
The reason I mine this way (instead of with ASICs or dedicated hardware) is because this is all equipment that I would have bought anyways for gaming and/or programming work. I do a lot of gaming in 4K at 120 fps, and the RTX 3090 is pretty much the only video card that can actually pull that off.
Being able to toggle the gaming rig into mining mode whenever I'm not actively using it means that the equipment pays for itself. It's a lot easier to justify spending $6,000 on a gaming rig when that same gaming rig earns you over $100 a month worth of passive income!