How does such a person know what's "too much"? Absent a reasonable working model of costs involved in infrastructure projects, it's all going to sound like too much.
And past a certain point on a spectrum of temperamental tendency to attribute laziness or wastefulness to other people, the working assumption is going to be it's boondoggles all the way down.
The only way to fix this -- if it can be fixed -- is reinforcing narratives about the value of projects and measured collective values.
Costs above initial estimates should only happen when there's an unknown (e.g, digging discovered a really hard rock layer that nobody knew about). Or weather issues beyond prediction (like tornadoes or hurricanes).
How, other than by buying everything you need up-front, finding a place to store it until you need it, and hoping that it is still usable when you do?
One other piece I haven't seen mentioned yet: large construction projects that take years to complete are incredibly hard to estimate accurately, because unpredictable economic swings can cause the cost of items to vary quite a bit between when the estimate was produced, and when the work was actually being performed and purchased.
This was one of the reasons why the Big Dig's estimates were so far off. Although there are a dozen other factors with that particular case as well.