Pleco was started back when mobile was much smaller; Palm OS programming was so difficult that we were pretty much the only game in town, so we became well-known simply by dint of existing at all; this was also a time when Chinese learning tech was in its infancy in general, we were years away from Skritter or Anki or ChinesePod or any of the other apps / websites that helped to define that market as it exists now. (heck, Pleco pre-dates podcasting itself by several years; the first iPod was launched a few weeks after our first app back in 2001, podcasts only started to take off in 2005 or so when Apple added support for them to iTunes)
Plus, licenses were much much cheaper; there's literally an order of magnitude difference between what we would have to pay up front to license a dictionary or handwriting recognizer or whatever back then and what we would have to pay to license one now, despite the fact that now we have to tithe 30% of our revenue to Apple + Google and our margins are a lot lower even outside of that (royalties are a much higher % of sales).
I didn't need to tap anything but my personal savings (which as a middle-class college student were quite modest) to get Pleco off the ground, but if I wanted to launch something like Pleco now it would take a ton of capital and I would probably likewise need to tap Kickstarter and investors to put that together, and after all that it's far from certain that I would actually end up making a profit. Outlier isn't quite the same project (not much programming involved) but they face most of the same challenges ramping up something as ambitious as what they're trying to do in as crowded / competitive / generally insane market as this is now.