VW did not invest that money. That was the penalty they had to pay from Dieselgate [1]. The network is now seeking $1 billion in capital investment [2]. DC fast charging isn't profitable due to utility demand charges (for drawing 100-300kw on demand), so networks like EA will likely eventually fail being unable to obtain capital financing [3]. Tesla runs Superchargers as a cost center, and only needs them to break even, as their business is selling vehicles.

TLDR Tesla sells an ecosystem. They are the Apple of EVs.

[1] https://www.cnbc.com/2019/05/10/vws-2-billion-penalty-for-di...

[2] https://electrek.co/2021/07/07/electrify-america-rumored-bil...

[3] https://www.utilitydive.com/news/nearly-all-high-voltage-ev-...