Quixtar is not a pyramid scheme. The sine qua non of a pyramid scheme - a legal term meaning it must have this feature - is that you are paid for recruiting other people into the scheme.
In Quixtar you only receive payment for the sales of products by yourself and by and to others you introduce to Quixtar. Recruiting additional Quixtar reps is a marketing strategy for increasing that sales volume, it is not something you receive payment for doing.