Certainly don’t disagree with Blossom that doing what you are good at and/or love makes sense. But sometimes kids discover that what they thought they loved in HS and wanted to do in college, is not what they end up wanting to do. Or they decide that as much as they love a subject, they don’t see a way to earn enough to support the lifestyle they also want. Or they find that there are kids much more dedicated and much more talented/gifted than they are.
While it is harder to succeed if you have a lousy background, it is not impossible. Kids from bad high schools end up successful, but often are either incredibly intellectually gifted and learn the material on their own, or are able and willing to take advantage of tutoring, office hours, and other supports. Unfortunately some don’t and will opt for easier majors
The idea that you have to be “good” at something to be successful is one reason girls tend to stay away from math and hard-core science. The attitude that anyone can do well in those subjects, if they are willing to work hard, is generally true - except for the rare individual that has some sort of LD. That doesn’t mean they all WANT to work that hard, however.
Virtually no one gets to be at the top of his/her field without a lot of effort.