They have persuaded themselves that fat is an immutable trait, like skin color, and therefore  so calle "fatphobia" (not wanting to hire or fuck them) is a "civil rights issue"/unjust prejudice. That's why they happily appropriate the language of actual civil rights movements , the gay rights movement , etc, and really and truly equate themselves to members of those groups (even though megafats were very rare, prior to the mid 1990s or thereabouts). IOW, their problems are all  self inflicted, a fact of which they are trying desperately to remain in denial.