Off-topic, but this really stuck out for me:

I’d set this bar at 50-70% net profit margin. We can aim high because there is no additional cost for each new customer once we reach profitability.

That's a common misconception. You are indeed spending money on getting each additional customer, you are just not accounting for it correctly. It's easy to consider all marketing/advertising/sales/customer service expenses as fixed costs, when indeed these costs go up with each additional customer you on-board.

Also, even if you reach the 50-70% profit margins, how sustainable would that be? The simple law of efficient markets dictates that you will have competitors who will be willing to undercut you. There is no relatively stable company out there that is able to make such margins unless they have constructed entry barriers around themselves (patents, laws etc.).