Remember too that any 7 year old laptop is going to be hit-or-miss. Yes, a ton of people are using laptops older than that, but electrical components do degrade over time, particularly in a portable computer. The risk of a mechanical hard drive failure (unless you're planning to upgrade), GPU failure, power supply failure, or other random hardware failure is much higher than a 2-3 year old computer.
Will it work fine today? Sure. But are you planning to keep it for 3-5 more years? That's where it could get dicey, especially when you're paying >50% what a low-end new machine costs.