Hello, Pierro!

Agreed. Although there may be exceptionally "strong" or "detached" individuals who are influence-resistant, I believe the vast majority of us absorb what's in our psycho-social environments, some more and others less.

In my own case, no matter how it began, depression has developed a life of its own and has not apparently diminished as I've withdrawn from most live negative influences. Nevertheless, I think your policy of avoiding people who provoke negative thoughts about yourself is a legitimate and perhaps necessary self-care measure.