The educational requirements for becoming an engineer vary based on the discipline you decide to pursue, but here is an example of what is needed to become a mechanical engineer, including median salary:
A mechanical engineer must earn a bachelor's degree (at minimum). Many who pursue a bachelor's degree in mechanical engineering also pursue graduate degrees in their fields. In addition, a license is required to practice engineering in all states in the U.S. This requires education, many different exams that must be taken, and supervised work.
Simply earning a achelor's degree in mechanical engineering opens opportunities to work in automobile companies, utilities companies, and even government agencies. Earning a PhD can open the opportunity to teach or conduct research at a university. Pursuing a higher degree can also open opportunities to hold executive positions in companies.