Oh, I DO trust you. There are other factors at work in the admissions process, especially at the elite colleges. If the OP wants to go to Harvard, MIT, Cal Tech, or some other such elite school, he’ll be competing against a LOT of people with very high SAT scores. So, the admissions departments can be very choosy. If the OP has poor high school grades, the admissions department may discount the high SAT score (“smart kid who doesn’t study or work hard- who needs more of those?”).
So, it’s true that the SAT isn’t everything, and the OP’s 1520 score doesn’t guarantee he’ll get into his favorite college. But if he DOESN’T get into his favorite school, it WON’T be because his SAT score was 10 or 20 points too low.