They already can! B.C.’s Medical Protection Act does not prevent doctors or clinics from operating on an exclusively private basis.
If doctors are being supported by the government, the law states that they can’t charge patients more than the regulated fees.
If doctors un-enroll entirely from B.C.’s public insurance plan (so they are taking no public money), they can then charge patients directly for any services at whatever price the market will bear.
In our current system, doctors can't make as much money as they’d like to unless they are enrolled in the public system.