The people who generally want to destroy a system and rebuild anew are usually clueless or have an ulterior motive.

It's worth noting that "destroy and rebuild anew" is a point of contention among anarchists. Some of us favor a revolutionary approach, but some (myself included) favor an "evolutionary" approach instead. Same end goal, just achieved through steady incremental change, rather than a big upheaval.

In practice though, success likely wouldn't fall cleanly into either category. There'd be incremental change punctuated by occasional (smaller) upheavals. But I guess all social change happens like that, really.