They'll drag on and on. Some people will get rich and powerful, but the people on whose behalf you're supposedly fighting don't really care about any of it.
They'd much rather have affordable healthcare and housing.
The "wars" for affordable healthcare and housing will also drag on and on. Because guess what, there are opposing sides fighting against each other on those issues too, and neither side will magically disappear or give up when one side wins a temporary victory.
It's truly bizarre that you think longstanding social issues can just be "solved" once and for all (if you truly believe that and aren't just trolling).
"If Christian evangelists did their job, then the whole world should be Christian." Doesn't that sound silly? It turns out that there are a whole lot of non-Christians in the world who don't want to be Christians, and they're going to do their "job" too.
You seem to have completely missed the point of why I mentioned them. We've now compared many different organizations and social issues. What they all have in common is that there are longstanding competiting interests on both sides, and thus an advocacy group doing its "job" doesn't entail that the opposition magically disappears. An advocacy group hasn't failed to do its job if it doesn't wipe the opposition off the face of the earth, thereby rendering itself irrelevant.
"An advocacy group should disband after one significant victory" is really an incredibly inane suggestion that could probably only be made by someone who doesn't like the advocacy group in question and wishes they would disband regardless of successes or failures.