It's definitely a challenge to work with founders who are what seems to be trying to figure things out as they go, which results into creative chaos at best or disorganized, aimless destruction at worst. Before concluding that this gig isn't for you, at the very least, make sure you maintain your own standards of quality and responsibility to do the best you can do. Try to be flexible and work with them. Sell them on your ideas as best as you can when you disagree with their always changing ones. But if they disagree, I strongly advise to be flexible and don't let the chaos shake you from your own high standards of professionalism to do the best you can. I'm old school, but I feel you still owe that much to them since this is a contract you agreed to take on. Who knows? If you show you're working hard, your client will begin to trust you more and more when you have a different opinion than theirs. Either way, if things don't improve, you can walk at the end of the contract, but with the integrity that you did your best.