So, the charging network is a business even though it didn't start that way. Should they have kept buying plots and installing the stuff to connect? Must be a reason they are not. Is it a good reason? Can't say, don't have the data. So about the risk. The Superchargers others are installing are not TEsla branded, so maybe that's a mitigation against?
And yep, integration is a huge money saver. Reduce the number of middlemen for your parts, reduce the integration cost and timeline. How does the Tesla specific SC network look in a year or two? No idea.