Our species has done quite the construction the past 100 years. The population went from 1B to almost 8B and we all need a place to live/work/play/drive our vehicles. Hence, concrete is the most used material in the world (after water, which is an ingredient of concrete).
On aggregate, we build more than we tear down. What will happen to all those mega skyscrapers and infrastructure in 100–300 years? The cost to tear them down is similar or higher than building them.
The problem with buildings and infrastructure is that once they’re there, they’re there. They are built with a mid term plan but have a long term lifespan. We have to live with the architectural/infrastructural mistakes of the past.