Actually it would not have been pointless at all - even back then. A well-organized movement - or even a few highly principled actors in the courts of power - could definitely have, if not entirely stopped -- at least helped bring an early end to slavery and the colonialist expansion that started around exactly that time.

In fact it is getting over exactly this kind of cynicism that may be all we need to turn this situation around in a generation or two (and I do think we can do it).

But if everyone were to give into the same sense of resignation as you have - we won't stand any chance at all.