Wouldn't it be the team? I mean they're the ones responsible to the development to the marketing the release after all. Investors are just there to slap the money to the teams hands so that they can use it to either improve/reduce the time it takes for the project to develop or to market the coin itself. Investors rarely have a say, or at least full control of what the coin would actually do moving forward. They have some sway in it, but that's about it. In the end responsibility would 100% lie on the team that handles the coin 24/7.

In a sense you can say that investors are simply the money involved, the brain is the team behind it itself, and the brain is the one that makes decisions on how to spend the money, not the money itself.