I'm going to argue this one because I used to build my own PCs as well, and they were good upper-middle-class machines running upper-middle processors and video cards as well as the best RAM for the money, not the most expensive, but just below the price break-point. I usually spend about $1000 to build the machines and then bought a new video card about every nine months to keep it as current as I could without getting ridiculous.
Problem was, even on decent hardware, the machines needed weekly scans and daily updates to avoid malware and more than once I would need to replace a power supply as well, despite going as high as a 450W power supply on a 1.7Mhz processor machine that should have been fine at 250W. It's not like I overclocked or anything.
I've now been using a 2.8Ghz iMac for a hair shy of 2 years. I've not needed to upgrade the video card or replace the power supply. I've not needed to do weekly security scans and my AV (yes, I use one just in case) updates fingerprints once a week, if that often. In other words, I haven't had to spend another penny on my iMac since I bought it. This, to me, demonstrates a far higher ROI than even a scratch-built PC costing $1000.
Apple has earned my business by always providing me with a reliable piece of hardware and an easy-to-use operating system that allows me to run my business and my leisure on one machine.