This is very true and would represent another aspect that's hidden whiten the great list of questions when seriously getting into mining.
@Jtalk4456
What's your experience with system building/trouble shooting?
What does power cost, do you know how many amps/how large of a psu you can plug into the wall?
Where is the system going to be placed, if using stock coolers and planing to keep this in a bedroom is going to be very unpleasant if not dangerous to some extent with poor ventilation/cooling.
What's your plan for redundancy, noise, cooling, fire suppression?
This just scratches the surface of what your asking, all of this before looking at actual hardware/mining/mining software/drivers/card memory limitations/temperature bottlenecks/securing your wallets/exchanges/trading.
Though while it's really easy to build and setup a mining rig I would not recommend building a rig only for GPU mining. When the markets see great lows everyone panic sells, if you plan to gpu mine you need to be invested for the long haul and not for the short term highs.
Mining on a gaming rig is pretty simple, but setting up a dedicated miner is an animal of it's own.