If the cost to acquire a customer is $200 and taken in the first 6 months of finding a customer lead and the average customer brings in $100/year and stays for

If the cost to acquire a customer is $200 and taken in the first 6 months of finding a customer lead and the average customer brings in $100/year and stays for 5 years and starts becoming a paying customer after an initial 6 month sales period then you will not be profitable easily as long as you continue growing. It'll take 30 full months to amortize the net cost of acquiring a customer down to 0. That's a long time. Also, if your growth accelerates you'll just keep digging deeper and deeper into a hole.