They sold aprox 90,000 cars so far. Let's assume the vast majority was bought with Supercharger access. So that's 90k * $2000 for supercharging per car. With an average cost of aprox $150k per Supercharger, there should now be 1100 Superchargers. There are only 437 so far. Just a little over 1/3 of what they could have done and had the money allocated for. Once built, the cost of running them is pretty small, yet they will continue to cash in $2k per car sold in the future. What worries me is that they are far behind what they could have, but even more so, looking at their 2016 map compared to 2015. Looks like they rate of adding more is slowing down.
One thing that I've been told is that it's not the money that's holding them back from putting in more Superchargers, it's actually local governments, permits, and electrical infrastructure that holds them back. Or, in one case, a lawsuit that gets filed in the middle of construction. I'm sure Tesla would have loved to have 1100 Superchargers by now, but sadly local jurisdictions don't always agree.