DH Gate is a B2B directory, just like Alibaba, Trade Tang and so on. This site feature suppliers who list there, they are not suppliers themselves.
When it comes to doing business with any B2B site, especially with a chinese supplier, you need to research the supplier you want to do business with, and not DH Gate or B2B site themselves.
If you go ahead and do business with any one of these suppliers listed, you need to choose a safe payment option and credit card is the safest of all.
If you pay by credit card and you are not satisfied with the purchase you have the option to file for a chargeback on your purchase.
Note: I have not purchased from any B2B suppliers.
HTH