yeah, he said that the RX series are not durable like the GTX series. The RX 470 is used for regular browsing and games but not in mining so I guess it's a good dealThere's nothing wrong with RX 470s. Why does your friend say it won't last long?
I guess if you're buying it used it's probably going to be a couple years old, and may have been used for cryptocurrency mining. But as long as you're able to verify that it's 100% functional before you buy it (or buy it somewhere that has a good return policy or buyer protection), I wouldn't have a problem buying a used 470 as long as the price is right. But that applies to pretty much any used graphics card purchase.