Anymore, I imagine most people are just utilizing the upgrade models for their carriers and either getting these flagship devices with a trade in for essentially free (with monthly discounts) or with a nominal payment, after paying the sales tax. If people were paying full price for phones, only the true enthusiasts would bother paying for a $2000 phone. Those deals usually do basically soft lock you into their plan for the duration unless you want to pay off the remainder of the phone. But if you're not planning to switch carriers in the next two years and you can upgrade to the newest flagship or the last Gen flagship paying only the sales taxes on it... why not?

Also, sometimes there is some feature exclusive to the flagship beyond the processor and ram that makes it valuable. Anymore that's usually just the camera quality, at best, but if that really matters to you, then that can be a good reason to go with it.