The best answer to this question is “false.” This statement may be true for some kinds of interest groups, but it is not true for many other kinds of groups. Therefore, we cannot say that it is true overall.
It is true that some policy entrepreneurs have been very important for their interest groups. These are people like Candy Lightner, who founded MADD and helped that organization grow when it seemed not to have many resources. However, there are also many other kinds of interest groups that do not depend on this kind of charismatic leadership. For example, economic interest groups generally do not need policy entrepreneurs as their members are well motivated by their desire for economic gain. In such organizations (which are more numerous than organizations like MADD), there is no real need for political entrepreneurs. Therefore, it is best to say that this statement is false.