Not true, since there isn't an infinite number of blocks that can be generated within the time span of a difficulty increase.
The maximum number of blocks that can be generated between difficulty adjustments is 2016 blocks, at which point if they were discovered all in 5 minutes, difficulty will adjust accordingly.
The opposite of what you're saying could happen though, in that someone could nerf the mining market by essentially DOSing mining by introducing MULTIPLE TERAHASH within a single 2016 block span, then pull it. At which point difficulty could double or triple, making the next 2016 block span take so long that it would obliterate mining returns.
So basically, mine in moderation, because if one were to mine with an "uber rig" not only would it make them a brief fortune, but ruin costs and the community. I can see that.