Don't talk as if this is the only forum that tackles about bitcoin or crypto because there are people that I met who literally engaging in Crypto for long years now but has no Idea about Bitcointalk not until i mention this to them so it is not about this forum or other forum but on how they are engaging in crypto and how they are using it.
and also the arrival of New People in the world of Crypto is not arrival in Bitcointalk, but those who have been searching and learning about this time after time.
You are right, bitcointalk is not the only forum that discusses bitcoin because there are many other forum that discuss the same thing out there. But you need to know that bitcointalk is one of the largest bitcoin forum so far among other bitcoin forum which will be the most comprehensive forum among other forum. I agree that not all crypto and bitcoin lovers have 1 account in this forum especially if their interest in bitcoin is as a trading and investment asset. They can study elsewhere and that's not a problem for them.
For the record, I have some friends who are quite active as traders since 2017. They make profit through their trading activities but they don't have an account in this forum. They can learn from friend to friend who was also a trader before them, and I think they are fine without being active in this forum.