YikYak baffled me for its entire existence, their product was incredibly simple from an engineering standpoint, they had no clear route to monetization and followed in the footsteps of several apps that shut down due to bad press. (Juicy Campus, College ACB) Yet they were able to raise an insane amount of capital from several respectable VCs. If there isn't a clear answer to how does this company make a million dollars they shouldn't be able to raise multiples of that amount.
Don't know anything about it really but it seems like greed killed this yikyak thing. Why did it have to be a unicorn when it could have just been a really nice pony? It could have made money selling anonymous polling data, sentiment, zeitgeist for marketing purposes. Everybody wants to know what the young folks are getting into next.