They charge a lot of bigger batteries
If you can't just "
I want the biggest/best" afford it the maths is tricky and only favours relative frequent long distance drivers who value their time. £10,000 for an extra 50 miles range is 200 quid a mile
My typical Supercharger visit has most of the people who were there when I arrived still there when I left. I assume they are either smaller battery, or tight and want free juice.
With bigger battery I can:
Go further Natch! So some trips I don't need Supercharger (but would with smaller battery)
I go further before charging, so I need less at a charge
I can skip Supercharger - so I can reach one that is further away - that might avoid detour (to the nearer one), and I will charge faster because my battery will be closer to empty
I charge faster - same %age-per-minute, so with bigger battery that is more miles gain per unit time.
The 20-mile just-in-case buffer has less, percentage-wise, impact on my total range
I charge less [often] (for the same miles driven), so at 100,000 miles I have less degradation ... I think
I put a value on that with my Man Maths Calculator and it came to £10,000 ...
... comparison of 0-60 times had nothing to do with it
I had a similar conversation with my Sprog about SR+ vs. LR. She has one frequent trip which needs 4 minutes charging in SR+ ... and the Supercharger is right by the roadside ... so saved £10K there ... but if she has to start driving all round the country for work we will regret that decision (although Model-3 CCS far better suited to 3rd party charging than my Model-S...)