How Could This Happen?

Very Easily. This sub has been consistently wrong for several years now, particular the users who parrot the respectable opinions of our authorities and intellectuals (who were either lying or deluded).

Our Elites and the Left have been repeatedly found to be lying to us about multiculturalism and diversity. From No-Go Zones, to Grooming Gangs, to Sexual Assault rates, to Cologne, to the future of the Cockneys, to the age and sex and nationality of the refugees. This is the demgraphically determined future of the continent on the line here. Yet these stunning displays of at best incompetence seem to be forgiven, whereas any mistake made by their populist opposition is furiously upvoted to the top of the sub by the Left wing userbase to assuage their cognitive dissonance. The same goes for any grotesque story of what adding the third world results in versus some new shred of ivory tower virtue signaling.
Insert Sweden Facebook Rape versus Pope comments

But more simply: you spent more time agonizing over the past than securing a future.

To this end you muzzled your sheepdogs because they were prejudiced against wolves.

And spent more energy sobbing about Le Pen than outraged at the latest terror cell or grooming gang

Basically, you destroyed your in-group for the sake of out-groups, who still hate you for being part of your own in-group.

Or you just did nothing but undermine people from your in-group from protecting the in-group, justified with what I am sure was very sophisticated sophistry.

Even if the groups you evidently prefer were disposed towards universal tolerance, nobody likes a traitor or coward