Even projects whose term is more than the span of a human life can be kept under satisfactory control.
However, we must consider the fact that controlling a long-term project requires quite a different approach as compared to controlling a short-term project.
Feasibility study launched for the Messina bridge
Sometimes the owners do not really own the time span needed. In some cases the original budget is deliberately estimated lower on purpose in order to get a positive project decision.
For example, without such falsifications, we would not have St. Peter's in Rome nor St. Paul's in London. Both were heavily underestimated at the beginning. It is not known whether this was done on purpose. However, if the final total cost had been known from the beginning, it is highly likely that nobody would make the decision to proceed, and the World, today, would be much poorer as a result.
Of course, we must be aware that the capability of human beings to foresee the future is extremely limited. At best, most of the instruments we have only allow us to project the past data towards the future, sometimes with parametric indexes that allow for variations or sensitivity analysis. Moreover at the early stages of a project, many of the details are unknown and the total scope of the project is unrecognized.