Like you I have a great passion for cars, so in Feb this year I sold my 2017 Focus RS to fund starting this business and follow that passion, as a result of that decision I’m currently driving a....Peugeot 307 CC
Like you I’m doing this alongside the day job. I also bought and sold a lot of cars over the years, sometime just changing my personal car, sometimes purely to make a few quid. This time I’ve done it all 100% legit, VAT registered, warranties etc etc, and I have to say it’s a lot harder to turn a decent profit now.
Its not all doom and gloom though, I love doing this, love buying, selling and even preparing. It’s a lot slower than I ever thought it would be, I only have 3 cars though so that doesn’t help. Like the others have said, £100k sounds about right before you could get serious momentum doing this. I can honestly see it taking me 5 years or more before I could do this full time, unless things picked up at some point.
You do sound like you’ve got a sensible head on you, especially for your age, that will definitely help. Try to see it as a hobby to begin with, enjoy it, keep the day job going and maybe one day this will take over. Good luck with it.