Felix Felicis Fortuitous or Fraudulant?

[Adan]

Quickly put:

If "Felix Felicis" is so wonderful WHY isn't it utilized more often?

We have a potion that, if the taker listens to their amplified inner 
voice, makes everything turn out well.  Circuitous schemes unfold 
before them, jinxes and curses miraculously miss, love-lives realign 
to their liking... who wouldn't take this stuff?

Sure, sure, it's a really tricky potion.  It takes six months to 
brew.  Whatever.  Like apothecary shops and Wiz-Mart (Wizard Walmart, 
natch) wouldn't be all over that.  Surely they could brew it 
correctly often enough that it would be commonplace.

And yet, it's not.  A somewhat smarmy wizard that tends towards 
rapacity and avarice and is proficient at its production has used it 
only twice in his life.  Both days were "perfect".  Its only 
drawback, according to the same man:

"If taken in excess, it causes giddiness, recklessness and dangerous 
overconfidence," said Slughorn.  "Too much of a good thing, you 
know... highly toxic in large quantities, but taken sparingly, and 
very occasionally..." (p.187)

So why only twice?  That's not occasionally.  That's extreme rarity, 
especially given what supposed good it can do a person.  Seems to be 
the perfect once-a-year birthday treat.  So what 
haven't we been told about Felix?  

Does he pack one heck of a hangover that we have yet to see?  Do the 
ramifications of turning everything "right" during that 24-hour 
period somehow turn disastrous?  Or at least somewhat poorly?  Is it 
an issue of karma coming back to bite you in the buttocks?

This little thing is one that is causing a fair amount of 
consternation for me.  Because nothing is that perfect, and Herself 
is usually very good at pointing that out sooner or later.

Adan, who wants to know what the heck happened when Slughorn took 
Felix... though the queasiness tell her maybe it's best she doesn't.