When installing SQL Server 2017 Developers Addition, the install would get to the point where it needed to connect to the service to configure the users (and whatever else it does), and it would fail to connect.
This is my development machine, and I had uninstalled other versions of SQL Server (2016, 2014, 2012, 2008 R2) previously and rebooted. I tried removing C++ 5 and 7 shared component. I uninstalled SSMS. I completely deleted Sql Server in Program Files and Program Files (x86). I could not figure it out.