Career or suicide: please guide?

Growing up, I have come to realize that happiness is always achievable, and is not restricted by certain careers. My mother is a successful medical doctor and my father is a happy banker. But contrary to my parents' hopes for me to enter an intellectually professional field, such as medicine or finance, I am interested in fighting. I hate being restricted by my physical limits: I always try to force my body to perform beyond its capabilities. Often times, I easily get into a tenacious fighting spirit where I want to pit myself against undefeated fighters. I want to confront the biggest ****** in the world, and to warn God to either help me or watch me perform the impossible by unleashing and risking everything for a total, unhindered victory. My parents will be emotionally devastated if I become a boxer, but it is the only field that gives me motivation to relieve my emotional frustrations. I am currently taking multiple AP and honor classes, but I have trouble concentrating in class; therefore, my grades are merely satisfactory. So, from an educational view point, I am a hopeless loser being a senior--starting from August--in high school. I have decided to become a boxer or an MMA fighter after high school, and to attempt to specialize in pertinent fields. From a practical outlook, I will probably incur significant brain damage from the career and will be a destitute. But I want to fight and survive on loans and fight pays during my initial young years. And when my physique will wean because of age, I will commit suicide via drug intake. Honestly, my fickle belief in God changes based on my amount of positive perceptions of life. So, if he exists, he should forgive me for taking my life instead of facing the dire remainder of my petty life as a wearing, old remanent of a force of unbending will. Please offer your takes on my life plans. Should I follow my desires and disappoint family members and satisfy envious enemies? Thank you in advance.