Well, everything is not worth it until you experience something
that makes you change your mind. You may feel that a diploma is
useless now, for all sorts of reasons.
I know that, because I am now a poly student. During Sec 2
streaming, I choose to study Pure Biology and Combined Science. My
parents told me that if I choose Triple Science, life will be
easier for me in poly. Me, being a lazy person and stubborn person
choose not to, so now, life in poly is a bit hard. I sort of
regretted the decision, because I seem to know nothing as compared
with my classmates. But I learn a lot from them, which is worth
it.
So, if you really feel it is useless, quit school now, get a job.
Get a few years of experience and see if it is worth it. Don't
study for the sake of studying and get poor results and waste your
parents' money. Study because you are interested, you want to gain
knowledge or any other reasons.