The main reason I went from 1:5 petrol back to 1:12 nitro was the cost.
It is a difficult one. On one hand it is your money on the other I'm sure your parents want you to learn the value of a pound and would rather see some, what they would consider, maturity in you putting some money aside.
For example when I had my first "proper" job at 14/15 I was already starting to put a little bit of money away for my first car (1:1 not RC )
Maybe meet them half way? In your shoes I'd have a chat with your dad, explain that it is a hobby that you enjoy which beats spending you money on booze and fags like some of the kids I used to go to school with and find out what his issue is. When you have mortgages, bills and other stuff to pay for your mindset does change with regards to money. That was why I gave up on 1:5 petrol despite having a good job, my own home and a few quid in the bank, I simply couldn't justify it to myself.