Let's say we have this device that creates instantaneous pleasure, and we don't use it responsibly. Let's say we can create orgasmic states without the need of actual copulation. On a large enough scale (okay, I'm speaking of the majority of the human race) we could give each person with access to such a device the ability to satisfy all of their mental needs by jacking them in and letting them enjoy a powerful, continuous orgasm. This would of course undermine sex; you could get all the pleasure you wanted from it without actually having to deal with finding someone to copulate with. When we do this, we're of course implying that this new technology is more important than sex, and since sex is the primary reason why humanity still exists today, we could effectively find a way to undermine our motivation to survive. What I'm basically saying is that, under the right circumstances with this pleasure-inducing technology, we could kill the entire human race.

Yes, of course there are a multitude of limitations that would make such a thing almost impossible; availability, public acceptance, acceptance by the social/religious elite, et cetera. I'm just putting forth what I believe to be an interesting idea.