up to you
its really up to you, i mean you can always pick it up after the hsc (sometimes can be difficult), but if u really into a hobby dont give it up because you will find enough time for studies and the hobby (if youare really really in to it). Otherwise dont worry the HSC isnt everything but you wanna give your best shot and if you feel u need to sacrifice some things, whether it be work, play or money go for it.