The way you test the viability of your idea is by turning your desired goal (minimum success criteria) into a customer production rate. In other words, you're trying to determine how many customers you'd need to achieve your goal.
Here are the steps:
Use your pricing model to calculate the number of active customers you’ll need to deliver your minimum success criteria revenue goal.
Number of Active Customers = Yearly Revenue Target / Yearly Customer Revenue
Note: whenever possible, if you can get as close to the minimum success criteria with just early adopter segment, that leaves a lot of room for growth.
Use your expected customer lifetime assumption to determine your churn rate and calculate your new customer acquisition rate after year 3.
Churn rate = 1 / Customer Lifetime (in months)
Some average lifetime needs to be determined. Looking at what competitors are recording, you find on average how long people keep them before they switch. Those averages are what you're really looking for in the estimation. (e.g. Successful SaaS companies like HubSpot and Salesforce report a 4 average lifetime value)
Determine how many leads you’ll need to attract using your expected lead to customer conversion rate. (e.g. On self-serve SaaS you typically see a 1% conversion rate on average)
All businesses have a J-curve where profit trails revenue, and revenue trails traction.
Your cost-structure typically starts out high, but as you employ economies of scale, they fall over time. Costs have a floor, revenue in theory is limitless.
It is much more empowering to model your business in terms of revenue (in proportion to value creation) vs. cost structure.