Because if you give up after one try you'll regret it later.
Treat this as a learning experience and start over. Something went wrong somewhere. Start again slow and build back up little by little. We all have lost fish for no reason, it's upsetting. It bothers me when I can't find the why. That drives me to try harder and do it right the next time, even if I don't know what right it. It means I spend more time reading and spend more time paying attention to my tank. I'm not saying you didn't do this, just that for me, a death makes me want to try harder so there isn't a next time.
I really think if you quit now, later, maybe not this year, but later in your life you'll really regret it.