Would it be stupid to fail prt's on purpose to get out the navy?

Some civilian jobs don't care as long as you have the qualifications for that position. Now many gov't jobs will do extensive background checks on you and they may find out. It's probably best not to let anyone know you plan to fail the PRT on purpose either. If you had a history of disciplinary issues in the military, many gov't agencies will likely not hire you.

If you get thrown out of the military. You can kiss ALL government, state and city jobs bye bye. NO ONE wants to hire a bum that couldn't hack the military.

It was policy in my department to reject all GUH , OTH, BC and DD discharges.

it would be beyond stupid as it can and will be a criminal conviction of dereliction of duty/refusal to obey an order. that means an OTH discharge and ZERO eligibility for any local, state or federal government work .

as someone who has hired people before

I just throw applications from veterans with anything other than a honorable discharge in the trash

No.