That is a good method to make personal choices. But in the 'startup ecosystem' (pardon me) or the 'free market' the cost is privatized and the benefit of success is socialized.
The overall equation looks like this: success = (team1_success or team2_success or ... or teamn_success)
I was assuming that the calculation was from the standpoint of all society, considering most free software advocates consider themselves altruists. So our functions are the same in this case, and it is still possible for the project to not be a good idea based on expected value.
The overall equation looks like this: success = (team1_success or team2_success or ... or teamn_success)