"A cynic is never wrong, but an optimist is always right" is a saying my friends and I have. Chronic pessimists and cynics often see and say much truth about the world. But the optimists will succeed much more in their goals, business, relationships, and many other parts of life. They have a deeper set of values and philosophy that is more right, even if they get the particulars wrong sometimes.
There are tons of comments online that claim emotionally secure and mature people are ignorant or even irresponsible if they're not in perpetual anxiety about the world. The "you should be scared with the way the world is" type. Obviously, what they claim is not true, and it's very unhealthy. But someone who is emotionally secure understands they gain nothing from a neurotic debate online, so they don't call these opinions out. The opinions remain there, unchallenged, seemingly agreeable and prevalent.
Life entrenched in pessimism is also a bit contagious. Though I don't want to be unkind, I have to be honest: there is a limit to how much I can try to help someone with that mindset before they drag me down with them. Something I learned studying field medicine (and this isn't some secret in the first responder world or just general knowledge) is that you protect your safety first. If you arrive in a situation and add yourself to the casualty list, you are just not helping anyone: you get hurt, and you create more work. I think this applies not only to physical hazards, but also to emotional ones. One more depressed person in the world does not make it a better place for anyone.
It makes sense to exercise some caution, and most of our emotional brains understand that. This brings me back to the original point — it's hard for one to succeed anywhere if everyone's avoiding them (best case scenario) or being turned negative themselves (worst case scenario). Much remains to be said about the internet's role in this epidemic of negativity and various depressive disorder crises.