It's not entirely theoretical. I actually tested one minute of purchasing and extrapolated the results. I don't know how 1 minute is different from 25, except for more key mashing. Now that the gold rush is over, I'm not about to spend 12,000 seals on something worth 1g just to make my point; I'm using a more practical approach.

The seal cap is 50,000. At the rate I described, it would take about 2 hours to convert your entire stash of seals (to 4.1M gil). Two hours is the length two average music albums, or one of many longer-then-average films. If you use my technique, you only need one hand tapping the enter key, which amounts to just as much work as spamming a craft. How is it hard to believe people can do this when there are lv.50 crafters all over the place?

I derived the 12k seal value from the over-aspected cluster rush. You can hit Atomos four times in one cycle for a total of four clusters. 3000 x 4 = 12000. You stand to earn more through crystals, of course, but I was trying to illustrate how much you would earn in just one cycle even if you were terribly unlucky.

13k seals would be, like, an extra 1.3 minutes added. Closer to 25 minutes for 1.08M total.