There should be a way to start a new game with same character/stats/items with extra difficulty... like make it super hard.
Requirement should be: complete every side job, gig, vehicle, main mission, then beat the game. Upon doing so you unlock "psycho" difficulty and play with your same V.
Requirement should be: complete every side job, gig, vehicle, main mission, then beat the game. Upon doing so you unlock "psycho" difficulty and play with your same V.