I understand those thoughts and feelings because I have them myself. That being said, why do you feel like your hobbies also have to be meaningless or have no impact? Volunteering can be a hobby. So can doing something like coaching a kids’ sports team (if you like kids) or mentoring someone or something else along those lines. For me, my job is a way to help my family and other people who are way less fortunate than I am.
Also, and I know this is a “typical” response around here: Have you considered the idea that you may be suffering from depression? Most of the time when the, “why does this shit even matter” feelings hit me it’s because I’m hitting the depression stage of manic depression/bipolar.