Castles in the sky: simple to describe, impossible to build.

The value of them is self-evident; what's not evident is how impossible they are to build.

Every execution step reveals yet more complexity to navigate.

As you pin it down it swirls away.

Building the castle in the sky demands all of your resources and attention, distracting you from approaches that actually could work.

Companies with the resources to build them often get stuck in the culdesac of trying to build them.