Average person is dumber each year because high iq is negatively correlated with fertility. On top of that populations are collapsing due to below replacement tfr. There's a real danger that technical civilization collapses later this century. The problem is that all easily accessible fossil fuel sources are already used up, so restarting much later from eg. a late xix century level is borderline impossible - civilization will run out of wood fast and progress stops due to an energy deficit. Advanced semiconductor manufacturing beyond proof of concept requires scale unattainable by such a civilization.

In short, the falling intelligence trend coupled with running out of easily accessible energy means that most likely, either humanity escapes biological-planetary constraints this century, or becomes stuck in a low-tech hairless ape local maxima until the inevitable extinction. A very good candidate for the Great Filter.

Fossil fuels only exist in the first place because for millions of years no organism on Earth was capable of digesting lignin. As trees died they just became buried, eventually transforming into coal and oil. That process stopped the moment fungi evolved the ability to digest lignin. This means that there's not going to be another chance even in millions of years, whether for human descendants or some other intelligent species (racoons seem like a good candidate). Easily accessible fossil fuel energy is a one time event per planet.

There's less than 100 years to escape the trap and it requires sci-fi level tech, either advanced genetic modification of humans or superhuman level ai.

>In fact, if we follow this logic, less smart people should be unhappier, since they are in an even worse position to do something

Worrying about something requires realizing it's a problem first.