Joining the Marines!?

Okay so all my life i have always wanted to join the marines. When ever someone says what is your future like. i say oh im planning on making a carer in the marines and then retiring at like 40ish and starting or taking over my fathers insurance business. sounds like a good plan right? but could i actually make a career in the marines if i don't go to college? i only have about a 2.3 2.4 gpa. so i doubt i would get accepted in any college. does this seem like a good idea? i am currently a junior in hs so i guess i still have time to reconsider but its what i always have wanted to do. Either heavy artillery, driving around in a tank, or infantry.