I think the hard parts are: 1. figuring out what to build 2. for non-trivial/long-lived projects, figuring out how to build it in a way that makes scaling, it

I think the hard parts are: 1. figuring out what to build 2. for non-trivial/long-lived projects, figuring out how to build it in a way that makes scaling, iteration, and maintenance something other than a total nightmare. (of course, many projects are one-off projects that don't need to be engineered for the long haul)