To answer your question directly, the best way to figure our the optimal revenue model is by doing exactly what you're doing right now: evaluate the trends, challenges in the market and calculate how much it costs to build your user base relative to the revenue (potential) they bring in. Commonly if your CAC is out of alignment people start by focusing on the tactics through which they acquire (which to be fair is only natural.) I though like to start on the custom side and work my way backwards. Are you targeting the "right" customers relative to your opportunity in the market. Start by focusing on this question first and making sure you're targeting the right market for your app/service. Next, I would see if you can fractionalize that market further down into a more specific/narrow subset of potential customers. This should allow you to maximize what you are producing in terms of revenue potential and also cut down on the acquisition costs side since you can focus your nozzle more directly towards the target. The bottom line is dont overlook an opportunity to make sure your target market is clearly defined and confirmed/validated. And dont be afraid to question potential false-positives (i.e. just because someone will buy your service doesn't make them necessarily the ideal customer.) try to create multiple layers and variables of filtering that help you make sure you've got the right group of people in your sights.