wow sorry to hear that..i dont know about the $4000 truck -that dosnt make sence to me but without knowing all the facts, i am assuming your dad may be ( thats a big maybe) trying to pull the reigns in on you in an attempt to avoid having you go down the same path as your bro? i may be totally off base here but i had a friend who similar thing happened the parents oldest kid was so talented/ smart in school/ the most amazing self taught guitarist with so much potential… started hanging with druggies/ and then dabbled in it himself..before you knew it he was breaking into houses/no college/ and in big time trouble..now the younger bro is a really straight- arrow kid works out all the time big into sports but not as committed to any one thing, still trying to find his way in life… as of yet he hasnt made any decisions.. and the dad rides him big time..he is always sayng he is trying to avoid making the same mistakes( giving too much freedom, stuff etc) but in actuality he is pushing him away in the process…
you need to be the one to follow your heart and do what makes you happy. as long as you stay out of trouble,contribute to the family( whatever you all have agreed on) you are showing responsibility, have you offered to do stuff like mow the lawn, help your dad out with stuff(without being asked)?? something that will bring you together on another level..?? just a thought.
parents sometime need you to let them know whats on your mind as well.communication is key he may not even know how you feel…
good luck..