Better question here - who are you to judge this? A prospective employee is by no means forced to accept employment with a start-up where they're receiving a smaller share of equity than the founders. There is no grounds for any sort of argument of what is "fair" when you are on the receiving end of a job offer. If it's not fair, don't sign on. If you don't like the terms of the deal, renegotiate or find another one. The founders / current employees can offer whatever they would like - you have the ability to decide whether or not you want to accept those terms.