You're 17, don't live your life to pay back your parents. Their voluntary job was to do what they do.
Thank them by being a good person and grow up into a man. A good, intelligent man who is cultured and isn't another waste that's contributing a big nothing to this senseless society on this mudball planet. Why? Because every second you're alive you steam inexorably toward death. Use your time to make them proud if you wanna give 'em something.
You seem pretty selfless, pretty good quality for a 17 year old.






