I am going to go the cheater route and say it won't be any one bullet point mentioned above, but instead a combination of several of them.
My thoughts too. And I would add that in the long run it ultimately comes down to confidence, which takes time in the beginning, but should grow slowly but surely on an exponential curve that eventually gets crazy fast. Yes, confidence is the key, I think. Without it, there's nothing. Something that's proven to work in the face of all the failures we are witness to.
Yes confidence is huge. People didn't trust crypto a couple years ago. Now they can buy crypto using Robinhood. The times are changing and have changed. As you mentioned as confidence continues to increase, likely so will the amount of money in the space.