RCA cables are made video, left and right.
The cable itself is a 2 wire positive and ground.
Component cables are: Green, Blue, Red or YPbPr which are made up of coaxial cable (RG59 or RG6).
Coaxial cable have far better bandwidth capabilities than 2 wire. That's why the industry uses those kinds of cables for component. No conspiracy!!!
You can get away with using RCA cables in place of component cables for a 480p signal, but your image quality would be degraded for 720/1080p.
In a bind I have used RCA cables in place of component.
A good quality RCA cables' Video connection(yellow) is made of RG59 at best, so that is a good connection for the Green of component, which caries the Luminance signal.
Cheap RCA cables have all 3 wire as 2 wire
But why settle for second best when you can just get affordable component cables? Monoprice etc...
If you're really on a budget and you got some time on your hands, go by 30 feet of RG6 cable at your surplus electronics store and some RCA connectors, Google "how to make your own component cables" and BAMMM cheap good quality compenent cables.!!!