Just take a look at the percentages they apply for things like store purchases and the Monthly (charity gets 5% IIRC). The split on the widget was changed if memory serves, and there’s the referral system. Not the ‘friends’ link I share here, to be clear, the one aimed at influencers which pays out real cash, rather than store credit.
Additionally, they worked on increasing the total amount paid (the more you spend on a bundle, the greater Humble’s cut in absolute terms, if you don’t touch the sliders), e.g. top/fixed price tiers, seeding, weighting the average, and so on. Early times you could nail BTA stupidly cheap.
BTW, and on second though, I recall a similar discussion on a bundle some months ago, I think in that case it was the charity that was lower than usual.
Remember Humble turned into a real business, complete with investors (Sequoia), fairly soon, I’m not even sure HIB2 and 3 were still under the original Rosen brothers set up of the first one, even though they were very similar to it. They switched gears around HIB IV, is my recollection.