[mcv]

The company is not your sole responsibility. If the founders are making a mess, and it falls to you to make this startup work, you deserve a share of equity.

But do you really want to be co-owner if the founders are constantly arguing?

You are your own person. If it's time to leave, it's time to leave. I value loyalty, and if you first want to sit down with the founders and tell them to start doing their job, then do that. But if their mismanagement is destroying the company, there's little you can do to stop it. Unless you take over. Are there any outside investors? What leverage do they have?