I could be wrong, but I think aspects of RTX are only being accelerated by a small, dedicated, portion of silicon at the moment. This is gen 1 afterall. Work is improving presumably on two fronts: dedicating more/faster silicon to it, and accelerating aspects of ray tracing on other silicon. Ray tracing is coming to the next consoles for example, and they won't be using tensor cores.
Both of those lead me to predict the performance/£ is going to rapidly improve over the next few generations, to the point I would actively avoid going with these gen 1 products.