At least three reasons for the rise of conservatism in the last part of the 20th century?

First tell us what you think that word means. It is very annoying when people use words without clear meanings, and most or all "isms" are meaningless.

Example: If you want to change something you are a radical. After it changes, you want to keep it that way, so then you are a conservative. But nobody will tolerate a name change because you built up so much hate towards "conservatives" when you were a radical. So both words mean nothing more than "us" and "them".