Two major counterpoints, the second borrowed from de Grey.

1. I am young enough that a sense of mortality is not a true motivation to start things now. While I know about my mortality, I do not, in the visceral sense, believe it. My motivation to start things now instead of later is to experience the rewards sooner, not a foreboding panic of losing finite time. I suspect this is true for at least very many people.

2. The argument doesn’t survive a simple inversion test. Let’s concede every single disadvantage immortality might bring— lack of motivation, innovation, housing. Suppose we already live in that world. Would a reasonable solution be to introduce a massive, rolling holocaust (i.e. introduce into this world the concept of death)?