Yes and no, you just need to offer credits. The point is not about re-sellers (that don't have the need to spend what they earn on your service), for those you need $, it's about referral, and if you're selling FOOs, you're probably fine selling a FOO with a 15% discount if it also guarantees you another FOO bought at full price, or even if both FOO are at discount.

People accumulating so much credit to the point that they can't spend it is a non issue in that referral (like Dropbox) is meant to be scaling wide, for scaling tall you need a re-sellers system (like say what Amazon or OVH are offering).