$156k in SF for a contractor is garbage pay. You have to pay for all your own expenses. Maybe you'd net $110k after all taxes and expenses.

There's real contractors and then there's fake contractors which should always be called staff augmentation.

No real senior software dev contractor would accept $75/hour in the Bay area. You're looking at minimum $100/hour.

Although, "fake contractors" or staff augmentation, those can be paid $75/hour or less.