I haven't killed a button yet on any of my kindles. And I read a lot. My K1 from 2008 still has all functioning buttons. My K3 also and my basic. My old VCR from 1992 still has all buttons working.
I can't really think of any buttons on any device I ever killed. Maybe I need ginseng.
And even if I did wear one out, I'd just buy another reader with buttons. Because I need them. Simple as that.