Well that argumentation is really flawed. Really really flawed. Videogames decrease in value because the demand for the video game decreases. Same goes for dlc. When the dlc releases many people want it and the demand is high. When the deman decreases the dlc should decrease in price as well.
So yes, you just seem money hungry.
I don't try to talk about 15 EUROS dlc which last about 2 hours at most and value at the same time. That is not value, that is a ripoff and you know it.
Actually no it's not flawed. As mentioned there is a time window, as more time passes the likely hood of someone buying DLC for a game decreases, and altering the price won't affect that, because the reason they are unlikely to buy the DLC is because they have moved on. The period of time when they where thinking 'Oh man I really want to play that game and see more of it' has passed by. Creating a situation then where Gamers are waiting for the price drop is playing chicken with that point, it's going to come, you can't avoid it coming, when then have you passed the point where the number of people who won't replay your game and therefore buy the DLC has grown beyond where making the DLC is worth it for how much you'll get back?
Is it worth playing that game of chicken at all?
Those people who do replay your game after the next big one has come out, on the other hand or even a few years down the line have shown that well to be frank? They think the replay value is worth it, and are liable to pay full price for the DLC without too much concern a sale isn't going to sell that many more, and indeed still encourages the whole chicken game, maybe you run the occasional sale to catch people who are replaying but...
what about the rest of the year when other people are replaying how likely is it they will wait around for your DLC sale before moving on? Where as having it at the same flat price, avoids that whole issue, it doesn't matter when you buy the DLC so you may as well buy it now rather than 'Waiting' for the price to go down.
Or long story short, he was saying the point of Sales is to make more money by selling more but in the case of DLC regular sales or a decrease in price would actually lead to less DLC being sold, due to the nature of well the Games industry.