[tejcirkulate]

"To increase users, we need to spend more."

Its great that you left the sentence ended at "more" because generally the answer isnt in spending more money, its about discovering those channels that help you get your message and value prop to your target audience at very low cost. Ideally, the cost should really be "time" in that you should be able to spend more time on discoverig the channels than spending money(ads for eg) on such discovery.

My opinion veers towards revenue and hopefullly from existing customers rather than new users because its less expensive, you already have a relationship and a strong basis for this relationship is the value you are already adding for them.