It's mostly about anonymity.

When we can hide behind a username that's not linked to our identities, lots of people spill their guts. Sometimes their guts are pretty, but generally you're right: the idiots are the ones shouting the loudest, throwing their ugly guts around wherever they go. When they're AFK they usually try to hold it all in, so as to not alienate themselves from the moral majority... a moral majority that I do believe exists.

...can you still call yourself a decent person if your go to response is seemingly always silence?

It's typically futile to engage these people, especially within the "communities" they're frequenting. You aren't going to change many (if any) opinions, and you'll become increasingly infuriated in the process. Some of these people literally get off on trolling/baiting/cranking/whatever, they don't even believe the things they're saying, but if it gets you in a tizzy, they'll give it all they've got. The eradication of their shitty beliefs is a battle that will be overwhelmingly fought by the ethical institutions of our society and the wear of time. I'm not claiming we'll ever reach utopia, but every generational iteration is slightly better than the last.

Re: Your Post Title, I can't empirically prove which side is the minority or majority, but even supposing that the horrible people are a majority, we at least seem to have a "fake it 'til you make it" mentality that applies to how we conduct ourselves in public. This is stifling enough that the (very poorly expressed) horrible opinions and actions we've all seen online should die out... although never soon enough.

I usually tip-toe around these issues, so I'm a little bit clumsy in expressing my views. And yep, I'm a 20-something white male... the privilege is real, and it's not fair.