In SF you very likely don’t have a car and your health insurance premiums are covered by work. If you’re young you’re also not not a homeowner so you don’t have maintenance costs and taxes. Also many companies in the city pay for lunch, do you may not have food.

100k/2k a month after rent is certainly doable in SF. I know many people that make it work. Also if you’re making 100k you’re likely paying closer to 1500 a month and having roommates and sharing a bathroom.