Many high-end games tend to have pretty hefty system requirements, including video card, because there's a lot of things the game is trying to keep track of (like various NPC's, vehicles, ect.) & look great doing so. Increasing the screen resolution & using higher resolutions textures (to keep things looking good) compounds the processing demands (typically at an exponential level).
As for gaming laptops running around $1,000 & up is more of a challenge of building a high-performing system with good specs (so it's not acting like a potato), size (so you're not trying to distinguish details on screen similar in size like a 3DS), weight (Do you really want to get a workout JUST by lugging such a laptop?) & thermals (you don't want your lap getting a nice golden brown look that you may find on your food & the internals of your computer melting into a massive paperweight). Many laptops utilize proprietary hardware (mostly motherboards) & configurations (to help with the above-mentioned concerns), which isn't cheap... so you're going to be paying for that.
WITH THAT SAID, if you're willing to make some compromises, you can get a good mid-range laptop for around $800. The one component that quickly gets skimped on is the graphics card. While you may expect a Nvidia GTX 1060 or better on a $1,000+ system, you'll be getting a GTX 1050 (not as desirable, but still pretty decent) or an AMD Radeon RX 550 (considered bare bones, as it has an effective performance of a GTX 1040) on a cheaper system.
If you don't mind having "last year's model", you can get some decent discounts buying computers on clearance... which can get good system for up to 50% off, but it can be a gamble as others might be willing to buy it at a higher price (taking a lesser discount) as well fighting off resellers (those buying systems at steep discounts & then selling them at a higher price, but still less than full retail price).
Hope this sheds some light on the subject.