I don't believe it is a silly question at all. If we are nothing more than material beings living in a material world, then why shouldn't meeting my material needs be all that matters? Why should I care about anything else? Why should I care what happens to you or anyone else as long as my material needs are met?
It's silly because I've already explained why other things matter to me, and I've explained what those things are. Heck, if I didn't care about anything beyond my own materialistic needs, debating here with you would be a completely unnecessary waste of time!
I know you're determined to reduce the lives of non-believers to wholly materialistic existences devoid of meaning, but that simply isn't the case. We simply choose to live in the REAL world, not one created by superstitious ignoramuses thousands of years ago.