There is a cost to managing risk. However, there can also be a cost to not managing risks.
There is a cost to increasing the quality. However, there can also be a cost for not improving the quality.
There is a cost to hiring a competent project team. However, there can also be a cost to hiring ordinary or incompetent teams.
Similarly, there is an additional cost for extra pieces of documentation, discussion, meeting, feature, decisions, constraints, assumptions and so on.
Every day you make conscious decisions to invest in the events that add value to the project. It is not easy because it is all very dynamic.
This is one reason why technology projects are over budget!
You see, in the project world, everything costs!