Bitcoin going extinct would mean that people stop valuing useful and scarce things. Doesn't seem very likely.
Otherwise it would mean that something so much better than Bitcoin gets invented that it completely outcompetes Bitcoin despite Bitcoin having a HUGE advantage from coming first and having a global scale network effect already. This is of course more likely, but still very very low chance.
Since Bitcoin is valued (among other things) for its hard money properties, which leads to it increasing in value over time, the most viable way something like this could happen is if it became really hard to acquire bitcoin, and therefore it stopped being such a great place to save money with, and therefore fewer and fewer new people got into bitcoin, all these things making the price stop going up for the most part. But, I think we can say with quite strong certainty that Bitcoin is not going to start getting harder to own but rather will continue to get easier to own and use. Case in point, now the USA has Bitcoin ETFs so the largest economy in the world is no longer limited to getting access (at least as an investment) to Bitcoin through crypto exchanges. The ways to own or get access to Bitcoin, and the ways to use it, will continue to increase as Bitcoin continues to grow into a major monetary asset. And so new people will continue to flock to it, and it's price will continue going up, and so growth will continue, and thus, it won't go extinct.
Another option would be that Bitcoin ruins its reputation so badly, that people no longer want to touch it. I have no example at the moment, but given the social media crazyness, maybe someone comes up with a convincing fake news story or so..... and after that Bitcoin never recovers....
OK, I gave it some thought: Lets assume there are terror attacks and also porn websites with nasty illegal content which involved the use of Bitcoins. Now mainstream media starts talking about "Terror coins" or "Pedo coins" for weeks on end. Finally the government decides that Bitcoin holdings without proper KYC can be confiscted by the goverment. And Bitcoin holder face a minimum 1 year sentence if any of the Bitcoins in their possession is even slightly linked to any crime.
Not sure if Bitcoin would survise such a scenario......