Armchair Revolutionary

Armchair revolutionary is a pejorative term, to describe a person who endlessly criticizes the thoughts, ideology or practice of social movements or armed groups from a metaphorical armchair — i.e., from a mostly or totally inactive, theoretical position. When someone is referred to as, or accused of, being an "armchair revolutionary," it is always a term of abuse, intended to invoke a defensive reaction on the part of the accused, or to discredit the (political) ideas and/or practices that person subscribes to, or both.

Inherent in the meaning of armchair revolutionary is the idea that the person knows that their ideas require them to be physically involved in (political) struggles, but that instead the person chooses to be intentionally ignorant or dismissive of real-world issues and problems, in an attempt to continue believing in the false reality their views create. In this way the armchair revolutionary is often regarded to see the world in at least a quasi-idealist manner, i.e., one relative solely to his or her own perceptions, rather than bothering with what s/he should really do — to absorb the physical and practical reality s/he would be compelled to see around him/her if s/he stopped the alleged "(political) posturing" and became an activist in actual (political) causes.

Wikipedia