Did you ever publish anything? First year or two it is mostlu pushing marketing/pr, and the long tail of trickle of money is where the true earnings lie. Also, for many works of art it takes more than 2 years to produce a next piece, and even if it was less, it’s not sure if it will actually sell.
Anything below 5-10 years and you have literal starving authors. Anything less than 5 and you may as well abolish it altogether.
we have literal "starving authors" - they pretty much all need second jobs to survive.
for the authors themselves I don't see much difference between having no copyright at all and being thrown a few pennies on their work from amazon. either way the ability to make a living from those pennies clearly isnt motivating them.
the future jk rowlings of the world will still buy lottery tickets to fame and fortune whether or not she ends up being worth $20 million (weak/no copyright) or $1 billion (strong copyright).
If all the earnings are in the tail then what the heck is in the head? or are you talking about the case where sales are flat and it's all tail?