Okay, real quick-like, here's the misery threshhold hypothesis:

People remain mostly at the same level of happiness regardless of circumstances, unless those circumstances include something that's really disastrous or otherwise misery-causing. (Including so little money you can't afford food and warm housing, life-threatening illnesses, death and divorce, etc.)

So, in the absence of particular trauma (or above the misery threshhold, as I put it), we are basically as happy as we are ever going to be, and no lottery-winning or fabulous-babe-having or whatever will change that for more than a few months. (Research backs me up on this.)