Try and work it out. Walking away is the easy path and always there. See if there is someone you both respect who can mediate the disagreement. See if you can timebox the other partners idea to see if it will pan out. See if you are both willing to listen to the data to point you both toward the right direction. If you have that much money coming in already and the market is big enough, see if you can get to profitability and at least be default alive so that you can sustain these endeavors in the long run in case the other guys idea doesn’t pan out.