Look for monetization. Bandwidth costs money which makes torrents great since ideally everyone shares the burden.
Ads alone probably won’t cover the burden, so they either have a subscription or have another agenda. Some might be legit for a while to sell out to the highest bidder at some point.
That said, there’re some examples of someone just loving to distribute e.g. Wii or older games. They usually have really slow download speed though.
Kes