crowdsourcing can be sabatoged

http://nautil.us/issue/18/genius/how-crowdsourcing-turned-on-me

"However, the crowd was hopeless against a determined attacker. Before the first attack, our progress on the fourth puzzle had combined 39,299 moves by 342 users over more than 38 hours. Destroying all this progress required just 416 moves by one attacker in about an hour. In other words, creation took 100 times as many moves and about 40 times longer than destruction."

"While we take for granted the way in which social media scales-up our ability to mobilize crowds in unprecedented ways, we must confront the challenge of ensuring those mobilized crowds do not fall prey to mobs."

Life in general is like this. You can raise a child, send him to school and college, relish the outcome, and then some idiot shoots him in a robbery.  It sucks, but destruction is much easier than construction.