That's true, though personally I find a sort of warm feeling about the idea of my messages and content I produced being available for my descendants, beyond just my bank account.
I wish I had a way to see how my great-grandparents were. What their life was like. That I could check out conversations they had in a public forum. Or see what hobbies they had.. but life back then left no traces, so their thoughts were lost to time after my grandparents and my father went away. If they wrote any letters they were lost. So I'd be ok if one day one of my descendants has a way to see what accounts I used and they come upon this message when wondering about me. Like a time-traveling high-five from past-me to my relatives.