Thank you for your interesting comment! Actually, Epicurus did distinguish between what he calls “moving” and “static” pleasures, which is essentially the same distinction as the one you make in your comment. A moving pleasure is the (fleeting) pleasure that comes, for example, from eating something and satisfying a desire. A static pleasure is the pleasure that we have afterwards, when the desire has ceased and we are at peace. For Epicurus, though, opposite to what you suggest, the more valuable pleasure is the static pleasure, not the moving one. How can that be?
I think that perhaps your second idea provides a clue. Let us assume, as you say, that the pleasure of buying a car (a “moving” pleasure) is fleeting, and after a while we will get used to the car and it will cease to bring us pleasure. If this is the case, then indeed the pleasure of buying a car would have little value, precisely because it is temporary and fleeting. In contrast, the pleasure of being “at peace” with oneself, not hungry, not needing anything at a particular moment, is perhaps more lasting? I don’t know myself. It seems that we can get used to both types of pleasures and then not value them any more like we did when they were fresh: certainly not being hungry will be an ecstatic source of joy for someone who has recently experienced being poor and hungry, while it won’t impress someone who has never been hungry in his life anyway.
But anyway, that’s Epicurus’ point. That the moving pleasures are fleeting, and that therefore we should not consider them pleasures of high value. While the static pleasures are more lasting and therefore more valuable.
Thanks again for your comment!