Then, ask yourself and them how you can help. A larger organization has more room for responsibilities and career growth. Others among the original 30 probably feel like you do; see if you can demonstrate leadership by identifying and resolving the conflicts that may arise.
If you don't already do this, start a brown bag series where old and new devs can talk about their work; or just do hack sessions together. It'll help identify mutual strengths and weaknesses. And when the CEO sees your name on the emails going out on this, I guarantee it'll go well for you.
If after your best efforts to evolve, you find that your CEO and exec team is among the 90% who can't manage and execute growth and life becomes hell, all of which will become obvious soon enough, then you quit. But make sure as many as possible of those new employees have good memories of you before you do that.