Supercharging is for those occasions where you want to cover a longer distance. I assume for most people this is rare.
I figure I will use it 15-20 times a year minimum (assuming they are actually built). Depending upon where the stations are located, I might use it more. That compares to about ten fills in an ICE at $35 so over five years that's $1750. Charging (that many times for 150 miles) at home is ~$700.00 over five years. Compared to using an RV park, where the charges might be as high as $25, it's most likely to be a bargain. And it's 30-45 minutes vs. 5 hours.