Sure, but how can this game be successful when the toolbar is active / dominant in the browser only for a couple of days until the user downloads yet another crapware bundle?

I wonder if any of the toolbars have extra code to try and nobble further toolbar installers. Perhaps there is a coding war going on between the crapware providers, fighting to be the top of the URL-rewriting chain?

Likely they have. I had to completely wipe a Firefox profile of a customer because ten toolbars had messed up the search engines so hard that I could not add Google back.