Technically, all advertising is arbitrage between the value of the eyeballs and the cost to reach those eyeballs...Adwords and Facebook were swamped with arbitrage advertisers until they got better at relevancy.

Arbitrage by definition will stop working eventually. you are exploiting information assymetry and a market inefficiency.

Once better targeting is in place and mainstream advertisers crack the native cookie youll see the arbitrage die out like it did with Shopping comparison engines in adwords.