I don’t think spending money in other things like building up a PC is really a bad thing or a regret. I personally prefer having diversified interests. I think building that PC is still cool, rather than going all in on just a car. I mean, cars are definitely my big thing, but it’s far from the only thing I dabble in. And in many ways, cars are just an extension for other sub-hobbies.
So actually, another advice I would give my younger self:
Don’t focus too solely on just cars, otherwise time will fly by and you will be blinded to other opportunities in this world.