An engineering degree is a great platform from which to launch a career. They are highly valued credentials, and the skills involved in becoming an engineer are helpful in life. But there are no guarantees in life. A person could choose to make poor life decisions after receiving that degree which could derail their life.
It would be nice if a single degree were a guarantee to success, but there is no such thing. Even with an engineering degree a person still has to go to interviews, get hired and continue performing well at their job. There then have to be promotions available at that company or that person has to continue looking for a higher paying job at another company. Since these higher positions are not infinite, everyone with an engineering degree cannot possibly secure one, so the degree alone is no guarantee to success.