No, it's not like that.

I agree that the financial and legal situation is as you say. (Having written financial trading software, I know how to price a deal.) But that's the skeleton. The flesh is the human relationships. I personally feel more responsible to the people I hire than to the investors, in that their commitment is larger and the failure hits harder. But my sense of obligation also extends to the investors, and in all cases it extends beyond the legal minimums.

I think there are practical reasons one might behave that way: Silicon Valley is a small place, and one's reputation has a lot of value. But for me it's deeper than that: collaborative projects come with a sense of obligation to one's collaborators.