A society grows great when old men plant trees in whose shade they shall never sit.
Plant those trees, even if your life sucks, even if you have no children or family or your own. You never know who will end up using your good works for more good. The fact that they may not be used is not a reason to not bring them into this world.
Humans are in an endless battle against entropy. Anything you build for the sake of the future is a little win.
Does it matter if our names will be remembered with reverence for what we have done? No it does not, the act of giving the future opportunity to thrive is what matters most, because all of us have stood upon the works of millions of nameless men and women whose work supported our way of life. We don't know all their names, and that's okay. What matters is the evidence of their works, and those things will truly be remembered. (For good or ill)
Even if you don't have hope for yourself, please don't lose hope for others.