Why do some social movements meet with success while others simply die out or fail?

What will be an ideal response?

When members of a social movement come together, they lack many of the advantages that a small, homogeneous, and economically powerful special interest would have. The size and scope of a social movement, in theory, are so prohibitive that they should not exist at all, but they do! Part of the problem in whether or not a social movement will succeed lies in those inherent differences between interest groups and social movements in terms of size, scope, financial resources, and coordination. Another measure of success or failure may lie in whether a social movement is able to influence not just social policy but specific legislation. Since social movements are usually grassroots organizations, they lack the ability to focus on lawmakers with inside lobbying strategies and must, instead, rely on outside lobbying as well as nontraditional methods such as protest and political disruption. Sociologist Edwin Amenta theorizes that the reason interest groups succeed where social movements may not lies in the uneven power relationships that define interest groups and social movements. Most social movements fail because they combine ambitious goals with a severely uneven power structure, whereas interest groups are leaner, more focused, and better organized as well as being much better funded.