Interesting to hear all the young guns here asserting their independence.
I agree that it's his life and his choices. However, his choices are influenced by his history, family finances, and personal relationships with his parents. When you become a dad and have a teen of your own you may see the other side.
I have raised one and work with hundreds of teens over the years. Not many are very focused on what they want and have planned to get. ALL teens I have met want the nice house, car, pets, spouse, etc. A few may have a plan or an idea to get there. Even fewer have the guts, drive, and determination to achieve it.
There are many problems here and I have experienced it from many directions.
As a teen, all I wanted was my independence and for people to leave me alone. I took the first crappy job I could that would provide me with the income I needed. That decision has an impact on my life today, good or bad.
As a dad, I want what is best for my kid. I want her to grow past my mistakes and make her own. We have discussed the limits of my support as she makes her way in the world.
As an educator/mentor I see one problem with US society and the education system. We, collectively, tell the kids where to be and what to do until 18. At 18 and graduated, we tell them that they are an adult, good luck. Some kids just are not ready for that. Some can't cope with all the sudden freedom and choices. Some can.
The OP is at a crossroads. He is young and inexperienced. He is going to have to make tough, adult decisions. No way around it, someone is not going to get what they want. Only the OP can make those decisions.
I don't know many parents that can be reasonable about this. They have 18 years of money, time, and emotion invested into you. For the mom, it's all about emotion and love for her grown baby. For the dad, it's all about logic.
We have to respect the decision the OP makes, he is the one that will have to live with it.
Good luck.