I've been wrestling a bit with the concepts mentioned in this post as well (thanks @nomoreheroes7!), and I think you just nailed the answer. The 80/20 rule. That makes sense to me.
As for this comment:
The more users join, the more users will become whales and eventually reach more maturity.
Is that possible if the interest rates enjoyed by the whales today completely outpaces what's possible for new users to earn in a reasonable amount of time? What we might consider a whale tomorrow could be massively dwarfed by a super whale built up by interest on a whale's account today.
Man, I just need to pause a second and saw how freaking amazing it is that this community is, in essence, participating in real-time experimentation in free economic systems in open transparency. Anyone can take it over leave it without coercion. That's... amazing. :)