it is valuable primarily because there is an expectation that it can be monetized
your argument is circular. you are defining the value of attention in terms of money, then you dismiss defining it as a currency because (my interpretation) it is an asset or a good. it's like saying that the value of an apple lies in it's monetisation, if nobody buys it it means it has no value
attention has value because it's a resource. there's only number-of-people-on-earth quantity of attention at each moment to extract. if you don't extract it it's gone. you also need to compete for it because there's not enough for everybody.
the good news is attention is probably the less discriminating resource on earth. every human has exactly the same amount of it*
*caveat : the fact you have an equal amount of attention does not imply you can manage it optimally.
attention has value because it's a resource. there's only number-of-people-on-earth quantity of attention at each moment to extract. if you don't extract it it's gone. you also need to compete for it because there's not enough for everybody.
the good news is attention is probably the less discriminating resource on earth. every human has exactly the same amount of it*
*caveat : the fact you have an equal amount of attention does not imply you can manage it optimally.