You don't seem to have really investigated the question. We're at the least talking about identifying the prerequisites for feasibility using today's level of knowledge and technology, some of which will be developed to become much more powerful in the next 100 years. Within that timeframe, for example, we can probably achieve economical fusion energy generation and large-scale mining of selected (mineral-rich) asteroids. On the other hand, I believe that today's claims about imminent AGIs are quite overblown.

A lot of human social engineering must take place to focus humanity's efforts toward extraterrestrial, much less interstellar, missions. When a critical mass of humanity comes to understand that those projects can "pay for themselves" with a "dividend" that enables building a much better Earth environment, I believe that humanity will have turned the corner toward perpetual terrestrial sustainability.