Watch the video. It explains how Destiny actually makes use of operant conditioning to encourage you to buy each DLC and expansion.
If you are unfamiliar with the techniques of operant conditioning, here is a link to explain it in some detail.
http://m.simplypsychology.org/operant-conditioning.html
Edit: Thank you to Bant Spider for the video.
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Old news. And over complicated way of looking at games with loot drops and dlc content. Developers figured out long ago new content should drop every 4 months or players get bored a long time ago. The amount of money they charge you every four months (if you choose to buy it) is laughable to become upset over with how many hours you get out of it. If this makes you uncomfortable don't play mmos or and mmo like games. They all have progression, rng loot, content updates etc.