Why is it so difficult to capture carbon from the atmosphere?

Carbon in the atmosphere is a natural part of the carbon cycle. The problem though, is that through human activities, we are putting too much carbon in the atmosphere. There are many natural ways that carbon is captured from the air. Plants on land and in the ocean, all photosynthesise which takes carbon from the atmosphere. These are what we could call the ultimate and natural carbon catchers.
Scientists are working hard to develop effective approaches to capture the carbon that is produced from industrial processes such as power plants, and other carbon emitting activities like deforestation and agriculture. The challenge though is knowing what to do with it once it is captured. Storage solutions are needed but generally these are very expensive, and we don’t really know all of the environmental risks associated with them. For example, some ideas are to trap the carbon dioxide deep into the ocean, or to store it underground in rocks or in minerals. Each has a number of known and unknown risks which need to be carefully addressed before anything is pursued on a large scale.
Resource: https://scied.ucar.edu/learning-zone/climate-solutions/can-we-pull-carbon-dioxide-out-atmosphere