You might want to get out more. Climate-change concerns are amplified online like many other kinds of activism, but if you travel countries with declining birthrates, you'll rarely hear people IRL speaking of them.
A lot of this is just a difference in topics for conversations - local/global. See: us talking here about a Singapore dating app, when likely neither of us two is in Singapore and at least one is already married. On the other hand, people in my circle are worried about the climate change concerns and we're aware of that... but it's not often a topic of conversation. It's not the concern that's amplified, just the topic is more frequent. But it doesn't mean I'm not seriously worried about my kid having to migrate in later life due to local agriculture becoming not viable at scale, one of the dumb wars turning into ww3, or just dying due to one of the current climate effects turning into a feedback loop that we can't survive within the next few generations.
Not everyone is well informed about the realities of climate change, but many are and it's a concern I hear from normal people from the US, Europe, and Asia that I've met. Some bury their heads in the sand, and if you do you'll ignore others who haven't, but it's a very legitimate concern for people with a basic awareness of reality. Things have gotten far worse in my lifetime, probably older people are more concerned since we can see the changes more clearly, but not all young people are deluded or ignorant about the reality of climate change.