OP- I bet that half the kids in your town think they are majoring in CS. One- because it’s a hot industry right now, and two- you’re in California. I’ve seen this show before- in 2001, with anything CS or E-commerce related, in '97 with aerospace engineering, in 2008/2009 in finance and petroleum engineering, and back in ancient times- 1987- when the stock market crashed right before recruiting of undergrads kicked off (it was in October) and companies cut their recruiting targets to the bone. There was a recession in the late '70’s and early 80’s as well- and if you have older friends who graduated from great colleges summa cum laude and ended up baking oatmeal cookies for a year afterwards, it’s because NOBODY was hiring new grads.
Do NOT pick a college based on the ROI that you believe to be true today- that CS is hot, and that therefore your son wants to major in it, and that therefore in 6 years it will still be hot and that your ROI will be fantastic. There were cab drivers across the country with PhD’s in math back in 1987 who could tell you how “in demand” math was when they were in high school, in the “post sputnik but before Google” era.
Your son’s choice needs to be something you can afford. Period. And that is not unknowable like predicting the labor market in six years. Start there. What you can afford. The contribution from the grandparents, plus any contribution from you, plus the federal loan for your kid.