"And you didn't march because?"
That's an easy one to answer. There are some people who want to make the world a better place. They will do what they can, even if it's a small thing, like go on a protest, or pay £10 to a campaign, or sign a petition.
And there are other people who just want to sneer. They just like to sit there telling everyone why they're wrong to go on a protest or make a donation or sign a petition. And it will be because protesting is anti-democratic (these people have a poor grasp of history), or because they're protesting about the wrong thing (why are you angry about this injustice when you should be angry about this other injustice, over here), or because standing up for what you believe in is "showing off" or "attention seeking".
And these people then feel really good about themselves. Do they do anything themselves to make the world a better place? Of course they don't - that would be beside the point. No, their pleasure lies entirely in mocking and belittling the efforts of others. And when, one day, their grandchildren ask them what they did to stop global warming, or fight poverty, or protect women's rights, they'll be able to say, with a warm glow of self-satisfaction: "I didn't do anything. But I certainly made my point by sneering at people who did."