Number 1, yes there are people who hold because others are holding. They hold till price increases and they don't sell off, price crashes back again and they continue to hold. Answer to your 2nd question. Alot of people keep holding because they do not know when and how to sell off and then buy back quickly at cheaper price. My reason for holding is to make more profit when it appreciates in price. I do not want to hold for the sake of holding without making profit from it.
There are definitely people who buy and hold bitcoin cause others are doing same. I think those category of people do not or would not know when to sell cause the people they know who are also holding arent selling.
They havent got a mind of their own and do things cause others are doing it. They probably acquired bitcoin in the first place cause people they know are buying.
I think a majority of people with bitcoin assets are and have been holding cause of the ability to make some good profits.