Perhaps he could have a bigger impact if he founded a new company. If you have a brand new or revolutionary idea, that may be true. But if you have an idea tha

Perhaps he could have a bigger impact if he founded a new company. If you have a brand new or revolutionary idea, that may be true. But if you have an idea that fits into what somebody else has done, then joining that company and using it as a lever to magnify the reach of your work might be more effective. Another way to look at it is that in a startup you usually have to worry about a lot of things that are not core to the idea, such as marketing and productization. If you have other people to do that for you (as I'm sure Facebook does) then you are more free to focus on implementing your ideas to the best of your ability.