They justify it by continuing to sell at increased prices; "the market never lies". If a sufficient number of people buy at $84 a point, then it is by definition worth at least that much.
Another factor may be that price increases stimulate buying, in that people who are considering an addon may rush to do so before the price goes up. Or as in my case, some people may actually decide to join in time to beat a price increase! These effects may actually more than compensate for a slowdown in buying after the increase.