SaaS is a pretty simple business: You pay to acquire a customer on day one. Over time as you invoice that customer you recover your acquisition cost. From then on, the longer you keep that customer the more profitable they are. As the years go on and you keep more and more customers that you have already paid for, your business as a whole becomes profitable. Simple, right?
Tomasz Tunguz from Redpoint recently asked whether SaaS startups are less profitable these days. According to his data (below), no matter whether you sell to small companies or enterprise, over time the profitability of SaaS companies converges around a similar median.