Well… the fact that we’ll indeed never completely get rid of bullying shouldn’t stop us from trying.
As to what we should be teaching our children… How about both?
Standing up for themselves will teach them how many things are within their grasp and that some are indeed outside that grasp. It will also teach them that they need to try in order to determine which thing lies where.
Standing up for others will help them, all of them, live in a better world than we did. And that will be a world of victors, not victims. ‘Cause bullies don’t stand a chance if enough of us stand up when needed.

Wearing pink shirts and passing bylaws doesn’t turn us into victims. Refusal to stand up for someone else does. The bullies love that, they would just take us down one by one while the rest of us turn their heads ‘it’s not my business, let that pussy fend for himself’!

And yes, there is a second way by which we can become a society of victims. A short cut of the first one. Let somebody else take care of the situation. Instead of standing up ourselves, together, to let/expect somebody else do that for us.
That would be akin to inviting a bully to ‘take us under his wing’!