I agree that they're machines, with lots of integration between different systems, such as suspension and drivetrain.
But I don't agree that they need to be money pits, it depends how much you're willing to do for yourself.
Citroen ZX with a stripped timing belt and 3 bent valves - had it back on the road that same evening, cost 130 UKP
Rover 214 Si, blown head gasket - back on the road 2 days later following a head skim, cost 110 UKP
ALFA 159 1.9. EGR blocked and DPF drilled - done in several small stages, cost 20 UKP
Alfa 159 full set of quality winter tyres, 260 UKP
Alfa 159 rear discs and pads, 1hr to fit, 63 UKP
In spring I have the front discs to change and the cambelt, idler and water pump to do. I've budgeted for 200 UKP
Of course, you don't just start with a big job, but you start small and have a go. In most cases the worst that can happen is you need to phone a mobile mechanic to come and help