could it be they are the only ones that can afford $600 per day guided trips? MDs and tech nerds are well paid.

Nah, It's not even that much. $600 will get you a very good, 3 or 4-day guided trip to the backcountry in Oregon and Washington. You'd be hauling your gear, food and skies/snowshoes. I do think that techies can easily afford this stuff, but I also think what's more important is they can afford to take a lot of time off work (or just leave their jobs all together knowing they'll find another gig fairly quickly) to enjoy things like this.

Park is fun for me. It's relatively cheap too. You just need a ski pass and your gear. I would also qualify as a tech d-bag but I don't spend a ton of money on the sport and generally look like a dirtbag when I'm out and about

Depending on the mountain and the park, you may even be able to get away with just foot power.

Are these all in Northern California?

Not at all. There are high end touring and backpacking, i.e. full service guided hut/cat/heli drops and hut to hut style, all over the world in or near most major ski destinations. Most people I know who can afford to do these trips is within the STEM group or independently wealthy. Or they're younger with no overhead and they dirtbag it for a awhile to save up but this is the minority.