The Ministry of Magic never successfully tracked Voldemort. Even the very experienced and talented Order failed to track down the Dark Lord. Having several experienced potion makers, why didn't anyone think or care to use the 'Liquid Luck' potion, Felix Felicis? It could have been much easier to track him by doing so.
Besides the various problems making it that others have mentioned... Slughorn himself states the main problem:
From 1/2 Blood Prince:
“Why don’t people drink it all the time, sir?” said Terry Boot eagerly.
“Because 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 …”
Also, what is meant by 'Large quantities' may also be questionable; what's a large quantity, over how much time? Twice in a month? Twice a year? Twice a day? Even stretching it out to minimize the other effects, taking it on a regular basis could well be toxic.
Otherwise, everyone who could (including by purchasing it, so all of the rich) would be using it as often as they could be. Slughorn used it twice in his ENTIRE life; he's probably got good reason.
Making Felix Felicis is not the trivial, "hey, let's whip up a batch" process you seem to make it out to be.
In fact, according to Professor Slughorn, even attempting to make it is quite dangerous:
Desperately tricky to make and disastrous to get wrong. However, if brewed correctly, as this has been, you will find that all your endeavors tend to succeed... at least until the effects wear off. - Half Blood Prince, pp 187-188.
The implication is that even "experienced potion makers" aren't enough... you need top-level experts, and even then it is a difficult task.
Given that Slughorn says your endeavors tend to succeed, it is clear that it is no sure thing.
Then, as Slytherincess points out, even if they tracked down Voldemort with it (assuming that they could do so before the effects wore off), then what? No amount of Felix Felicis is going to allow someone to find and destroy all of Voldemorte's horcruxes.
It is very difficult to make, disastrous to get wrong, and requires six months to stew before it's ready to be consumed.
Note that Professor Slughorn, who was an uber-Potions teacher (either second to Snape or better?), has only taken the potion twice in his entire life. Since he was hardly concerned with major ethical angles of it, it means that either it was THAT difficult to make in large(ysh) quantities even for the best potion makers, or that the ingredients were so rare, or that the downsides were so severe.
Under the same logic of using Felix Felicis to track Voldemort, you could say "Voldemort and the Death Eaters should use liquid luck to triumph". What would happen then, if both sides use it at the same time?
The appropriate answer here is the one Fudge gave the muggle Prime Minister when he said that wizards could do anything:
The problem is that the other side can do magic too.
What would be the benefit? It is a risky to make, risky to take and the objective would you have you possibly finding where V was at the exact moment.
Then what? He will most likely have guards and traps to warn him of intruders (or do you think he would be defenceless) and even if you get passed them without him apperating or flying away ... he will probably kill you if you are lucky.
If they could feed the co-ordinates to the air force and have them bomb the area then I would be interested but that is not the HP way and, due to the Horcruxes, it would not work anyway :-(
There's a lot of stupid and dumb in the world, unfortunately.
Perhaps Felix Felicis could have been used to track down Voldemort, but, hmm, that's not particularly useful when VOLDEMORT CANNOT BE KILLED.
As others below me have pointed out, Felix Felicis is not an easy potion to make -- "disastrous if you get it wrong" and it takes six months to brew. It's not like it's available on tap at The Leaky Cauldron.
As I think about it, we don't really know enough about Felix Felicis to understand its limitations. Just because someone might want to murder another person, and takes Felix Felicis to facilitate his luck in succeeding, doesn't mean the potion automatically gives the taker whatever he/she wants. For example, would Felix Felicis constitute coercion under certain circumstances? Does the potion allow for that? Is it as innocuous as it is presented in Half-Blood Prince? We don't know if Felix Felicis always gives the taker exactly what he/she wants.
They might’ve needed more than luck - it’s all Felix Felicis gives.
When Harry wanted to figure out what form Draco was using the Room of Requirement in, he’d considered using Liquid Luck to help him. However, Hermione told him that it’d be useless, since it’d only help in a situation that he’d be capable of handling, but wouldn’t work to help him do something he could never do. It’d help him persuade Slughorn or win at Quidditch, for example - but Liquid Luck alone won’t make him able to fly unaided or break the Fidelius Charm.
“I think I’m going to take another swig of Felix,’ said Harry, ‘and have a go at the Room of Requirement again.’
‘That would be a complete waste of potion,’ said Hermione flatly, putting down the copy of Spellman’s Syllabary she had just taken out of her bag. ‘Luck can only get you so far, Harry. The situation with Slughorn was different; you always had the ability to persuade him, you just needed to tweak the circumstances a bit. Luck isn’t enough to get you through a powerful enchantment, though.”
- Harry Potter and the Half-Blood Prince, Chapter 24 (Sectumsempra)
Similarly, the Aurors, the Ministry, or the Order of the Phoenix likely needed a bit more than luck to find the Dark Lord (especially if they wanted to actually be able to do something about him once they’d found him rather than just knowing his location). Liquid Luck might not have been much use to them, especially given the effort and risk involved in using it. If they knew that they’d need more than better luck to track down the Dark Lord, they might not have considered using it worthwhile.