I don't know about the entryism, but I do know that many on the far left are very "ideological" persons. It's part of the subculture to *constantly* talk politics, and your ideology becomes part of your basic identity. "I'm a Trotskyist in the International Committee tradition". Sometimes, it's a form of evangelizing. In other cases, the leftist doesn't want to convince anyone but it's still seen as important to let everyone know his ideology. Some people feel right at home in this milieu. There is also a kind of ideological purism or purity involved. I suspect the "traditional far right is similar, while the new Alt Right seems more chaotic and frankly bewildering...

Tidlösa (Sweden)