Why aren't oil companies not the richest companies in the world if oil is black gold?

Many people refer to oil as black gold because of how costly and rich it makes people. It is believed to be one of the most important commodities on Earth. However, extracting oil costs lots of money. Oil companies are rich, but they may not be the richest in the world since they have to pay for equipment and labor to extract the oil from the Earth.

Also, oil companies must pay for environmental problems that they cause. This can lead to forking out millions of dollars every year. Even though it seems like oil companies make lots of money because oil is so needed, they also spend money in order to run this type of business and make a profit.