I find it funny that there are those that think a car hobby is like an investment.
In reality, a car hobby is a black hole you dump money into.
If you want to invest, then invest.
If you want to make money then start a business.
A hobby is a spending habit you have to regulate in order to afford.
If you love money, then managing it, making it, and/or investing it are the activities for you.
If you love cars then be intelligent: regulate your spending habit to limit your losses and keep it within a range you can actually afford so that it's sustainable.
In order to understand what that range is, you need to understand how much you can budget for it — which may or may not be obvious to everyone — but the much less obvious part of it is the ROI factor. For those without a business degree or acumen, ROI stands for Return On Investment.
This is where it gets tricky, because, if you aren't making money on your hobby, how the hell do you get a return on your investment? It's simple: your returns are in happiness and fulfillment. If your happiness and fulfillment are low, your ROI is low, therefore you need to get smarter about your hobby investment so that you reap satisfactory levels of enjoyment.
A real secret to hobby success lies in staying within your budget and getting the best HF-ROI (Happiness-Fulfillment Return On Investment) you can.