When it comes down to it, your options for making money are really somewhere on a sliding scale of:
- Sell something for high profit, but it won't sell terribly fast, and you won't get it terribly often.
- Sell something for low to moderate profit, but it'll sell fast, and you can get lots of it relatively easily.
This applies both to crafting (rare HQs vs. consumables) as well as enemy hunting (shiny NM/BCNM drops vs. stuff like crafting ingredients), as well as to any other source of income you can think of. Some things do still have better gil/time ratios than others, of course (those insect wings will never be in high demand), but the above is the general rule.
So when looking into money-making ways, average gil/time ratio is what you should be concerned with. While it's possible to, say, get lucky and get a PCC on your first and only Under Observation run (which would, naturally, be a big and pleasant gil/time ratio)... Under Observation, *overall*, doesn't have that impressive a ratio because of the low drop rate. It's just as easy - and much more likely - to go a *lot* of runs with nothing to show for it, which would give the BC a dreadful gil/time ratio. That's why the average is important, not the exceptional cases of really lucky or really unlucky people.
If there exists anything where it sells fast and you can get a lot of it easily *and* the profit margin is high... needless to say, once it's "discovered", the market balances itself out (since then lots and lots of people will do that, supply will outstrip demand, and prices will fall).
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