niche (n.)
A specialized market
M-W
Business (originally U.S.). A position from which an entrepreneur seeks to exploit a shortcoming or an opportunity in an economy,
market, etc.; (hence) a specialized market for a product or service
[OED]
Niche is used more broadly than commercial market to mean an audience or group of devotees and, more generally any group of people fulfilling some criteria (even detractors). However, I haven't yet found a dictionary that has caught up with this more general, non-commercial meaning of cohort.
So the mirror strategy is all about looking in the mirror and choosing
a niche of people who are like you.
David Steele; From
Therapist to Coach (2011)
You have developed a special unique niche of your own—a niche of
people who have become fans of your artwork.
RD King; Essential
Marketing Tools and Strategies
The drama playing out in the human niche of people at Sonfon is
not any better. People there reported increased rates of stomach,
skin, and respiratory ailments.
Richard Marcantonio; Environmental
Violence (2022)
Indeed, I don't know how many readers are acquainted with Atzeni given
the fact that the critical interest in his work has failed to go
beyond the niche of friends and readers that accompanied him
faithfully throughout his life.
Federica Santini; The Politics of
Poetics (2014)
A paradigmatic example if offered by Georges Brassens's fortune in
other European countries in the 1950s and 1960s: non-French
singer-songwriters (like Italian cantautori) began 'to be
influenced' by his songs at a time when Brassens was probably one the
least known auteurs-compositeurs-interprètes outside France (or,
rather, known only by a niche of enthusiasts, while other auteurs-compositeurs-interprètes like Charles Trenet and Gilbert Bécaud, had access to radio, television and the cecord market).
Isabelle Marc and Stuart Green; The Singer-Songwriter in Europe
(2015)
By the way, the philosophy of our team is to define the niche of
patients in whom the safety-efficacy makes it advantageous or at
least compares favorably with open neurosurgery.
Michael Lim et al.;
Handbook of Radiosurgery in CNS Disease (2013)
Allison may not be famous by the traditional definition; certainly
nobody here seems to recognize her. But to a devoted niche of online
fans—and an even more devoted niche of detractors—she is a bona fide
celebrity.
Joan Gorham; Annual Editions: Mass Media 09/10 (2009)