Just got this notification from Humble about another price increase.
They are losing business, because revenue goes down.
They will negotiate the prices they pay publishers for a set of keys to use in humble choice to mean they get their 15% cut of the revenue. If a publisher sets the price too high, they'll go elsewhere until they can get their margin.
If they lose ~25% of their subscribers over a ~40% price hike, they will be right back where they started in terms of profit—which is a place where they would consider hiking the price and losing customers.