A 65-inch model for $5000 doesn't seem entirely insane. I mean the market still is small-ish because that's a large size and a heady premium, but staying under the $5000 price (i.e. $4999) would make it feel palatable I think to a solid number of people -- myself included, if I were in the market for another 65-incher.
That 77 is really the grail, though.
There is no difference in HDMI cables. If you can see the picture without visible dropouts or sparklies, the cable is working at 100%. No other cable will display a better version of that picture. You're simply wrong if you think there is a better digital cable than one that is already working.