I am surprised anyone thinks that ESPN is even-handed. They are far left on almost any issue they promote or comment on. Their political slant comes from the top, i.e., from Disney, and everyone at ESPN knows it.
IMO, they thought they had a captive audience and could force their agenda on the "ignorant, bigoted, religious, racist, etc. rubes" in their audience and help us see the light. While probably a small % have unsubscribed because of this, it has contributed to the overall lack of desire for ESPN and has likely pushed many who were equivocating on keeping cable over the edge. And among subscribers, it has probably caused the audience of many of their offerings to diminish. There are also many other sports viewing options now.
Again, IMO, it's their prerogative to express any political view they desire, (I actually kinda agree with a few things in moderation), and it's mine to tune out, disagree, unsubscribe, etc. I guess, ironically, the only question would be whether they are fulfilling their fiduciary responsibilities towards their stockholders. Their political agenda means a lot to Disney. They are willing to bleed; the question is how much. ESPN only contributes about 1/8 of Disney's total revenue, so they can absorb a lot.