Downloading stuff for yourself: Okay
Downloading stuff for a 100% free game: Okay
Downloading to make a commercial game: Stupid (Don't)
While i don't think that there are any measures to control published products, especially because the content creators are all amateurs and hobbyists without access to law firms, it's just a stupid idea to create a business based on copied content.
If you want to earn subscriber money, buy the assets. Also worth noting that different stores have different rules. One site might allow rendered images with the cheapest license, others only allow "personal use" and require a much more expensive creator license. Some sites/licenses also allow assets to be converted and included into 3D games.
Which means that even if you buy a product, you need to read the fineprint because otherwise you'd still be in legal trouble just the same as pirating the product.
Also, pro tip
You must be registered to see the links
The best designed and most well-kept site. Has some problems with NSFW assets due to russian laws, so you apparently need to create an account there to see/download that. But it's not like there is a new NVG8 coming out every month or year.
The only downsides: The search function can only find keywords in the asset names; the preview images are limited to 1 image; and the asset description is always in russian. But their DL links always work, and you can always visit the original store for a proper description.
Alternatively,
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This site is often a mess with the "latest" uploads ending on page 2 and everything after is a bunch of old uploads which are mostly broken. However, it has a wider text search function which includes keywords from the descriptions. So if you search for e.g. "Egypt", it would include an asset named "Queen of the Nile" as long as the description contains "Egypt".
Render-State.to seems to be gone for good. It used to be okay for a while with some assets i couldn't find elsewhere, but it eventually turned into a mess of downloads hidden beneath ad links and other fishy stuff. Perhaps it was designed not as much as a enthusiast site but rather as attempt to financially benefit, which usually doesn't work with a fringe hobby such as DAZ3D content sharing.