Frustrating: Why does ATT not treat its longtime customers like it does new ones

Have been an ATT customer for over 10 years -- 3 cell lines (down from 6), Uverse, Intranet (fastest they offer), home phone and digital life.  Spending between $600-$700 a month,  I went into the store today looking to upgrade all three lines to the IPhone X (all three lines are eligible).  I was told that the only promotion they could offer was a BOGO free if i added a line (which I don't need).  When I asked if there was anything else they said they could give me $500 off if i switched from Uverse to Dish (Why would I do that?).

It is just so frustrating to see the company value new customers more than long time ones.  The Verizon store was our next stop.  We can basically pay the same monthly price -- and at least get more service ($60 per month and unlimited everything)  -- so we might as well move while we have the chance -- probably time to start shopping the rest of our ATT bundle as well.  While my business may not mean a whole to them, I just don't like being taken for granted so I will give some other folks a chance to earn my business.