Happiness is actually fundamentally flawed because it creates an inescapable spiral of failure.

Everyone is not happy some of the time, even those who are otherwise successful (good career, loving family, meaningful pursuits, etc). So, if happiness is a measure of success, then despite all those things, they're failing. Which makes them even less happy. Which means they're really failing. And so on.

How do you fix this problem? Definitely don't sacrifice anything to create a better future because sacrifice, in the now, doesn't make you happy. Don't excercise (because it's painful), don't spend time with your children (because they aren't perfect), don't try to fix any of your problems (because they're depressing). Nope, get high, have a wank, and play video games forever; because that makes you happy right now...