I’m going to sound like a noob; but, I am a computer guy. When a component goes bad, I buy a new one and replace it; I don’t rebuild the entire computer.

Why would I need to pay $2500+ to rebuild the engine for a damaged camshaft (ground lobes)? Why wouldn’t I just be able to replace the $299 cam (and maybe a few seals) like I would a faulty video card?

I’m asking because I want to understand the mechanics behind it. Eventually, as I get closer to military retirement, I’ll be doing more of my own repairs, cutting my costs a bit.