Sell Your computer and your interwebz
Your dad did support you finacially for the last 17 years, correct?
Well anyway, its your job and your money. Why don't you just go the bank and start your own account. Pretty sure you don't need to be 18 to deposit money in your own bank account and get an atm card for it. Money is money to the bank.
Whats the point of a camera anyway for you? Do you need it that bad? I think a car will serve you way better than a fucking camera. Make sure to film your friends as they drive past your house, ok?
This goes out to Miralgia becuase I couldn't quote:
Have you ever heard of something called a bike? If the kid doesn't need a car to survive like most other Americans think they do, more power to him. Get rides from friends who are willing and able, I mean why not? Oh and maybe he lives in a city with a good public transportation system.... crazy thought huh? And what is a camera to him? You're in the military right? What is your rifle to you? I mean I'm sure you enjoy shooting your rifle at the range and it is also a tool you use in your work. A camera to a filmer is something they enjoy using and a tool that enables them to do their job. So what if the kid isn't a professional filmer, if it brings him joy and gets him out of the house, I say go for it! Try something new... I mean I'm sure he's played with cameras before and knows what he's getting into.
To the OP:
Buy the camera. Keep talking to your dad and maybe tell him that you want to explore your interests and maybe you want to purse videography as a career. Talk him into it, you worked for the money, you deserve it.
Doesn't change the fact that his money is already in his fucking bank account that he wants to get it out of.