My family is not supportive?

nobody in my family is supportive of me joining the marines my mom thinks that ill either die in battke or live whever im stationed for the rest of my life and my dad doesnt say anything my brother thiinks ill get shot and my other brother hates the military( cause he got kicked out for being drunk in the barracks underage) and tells me that its not worth dien for a currropt sountry and tells me i wont get any money at all for 200 years and but the only thing m afriad of is gettins shot with a sniper rifle or blown up without knowing or dying in training before i even get to serve my country. what can i do about my familey and are my fears true.