Work full time, pay Medicaid and also pay my monthly 104 for Medicaid ins, why?

I think you are confused, or using the wrong terms. The current rate for Part B MEDICARE, not Medicaid is $104.90. You are paying for this because you have this insurance. Do you have other insurance through your employer? If yes, you could talk to Social Security about opting out of Part B for now. Do you really have Medicare, not Medicaid?

The $104 is for Medicare. Just about everybody who works in the US, has $ taken out for SS & Medicare; this is done via FICA. FICA underwrites the federal entitlement programs. SS amount depends on your wages but Medicare is a fixed amount of $ 104.90.

If a NJ Medicaid participant is Medical Assistance Only (MAO) or NJCare, the CM should ask if they are a SLIMB recipient. SLIMB is the government program for individuals with income greater than 100% and less than or equal to 120% of the Federal Poverty Level (FPL) and for SLIMB Q1, income up to 135% of FPL. Medicaid pays either all (SLIMB) or part of (SLIMB Q1) the Medicare Part B premium for qualified individuals. Ask your CM (case manager) if you are eligible.