I don't think buying a new phone is a waste if you plan on keeping it for several years. I still have an iPhone 5s that I bought new 5 years ago. When they were cheaper, upgrading annually made sense too because the scale of innovation was more rapid.
Nowadays, the innovations are less significant and the price has gone up. So, buying a new one and keeping it for 4+ years, like you would with most electronics makes sense to me.
I don't think they're too expensive either (expensive, yes, too expensive, no). The top end Samsung phones are right around that same price point. But if you don't need the latest stuff when shopping for a phone, yeah, it can make sense to just buy used.