This completely misses what the SAP business actually entails. No one runs "SAP". They run "SAP as customized for business X". That customization costs millions

This completely misses what the SAP business actually entails. No one runs "SAP". They run "SAP as customized for business X". That customization costs millions of dollars. It encodes every little specific thing about the business. Companies run their entire operation on top of it. It's impossible to replace, because it can't go down. Ever. An open source version would be only step one, and not that useful by itself. You'd still need to create the entire consultant ecosystem SAP has on top.