Milo Yiannopoulos had everything he needed to be a smash success in today’s conservative world: a big personality, an intuitive sense for baiting the left and no inhibitions about causing offense.

It hardly mattered that he did not consider himself much of a conservative.

But Mr. Yiannopoulos’s downfall this week — a dizzying 24 hours in which he lost his speaking slot at the pre-eminent conservative conference, had a book deal canceled and, on Tuesday, resigned under pressure from his job as a senior editor at Breitbart News — was a sign that in today’s political culture, when each day seems to bring a fresh lowering of the bar for decency and civility, some limits still remain.

His glib remarks about pedophilia by Roman Catholic priests and his endorsement of sexual relations with boys as young as 13 drew widespread condemnation from many of the conservatives who had long stood by him, even as he offended so many others with his insulting remarks about Hispanics, African-Americans, Muslims and Jews.

Mr. Yiannopoulos, appearing in Lower Manhattan wearing a sober suit and red tie on Tuesday afternoon, uttered the words that he had refused to say so many times before: I’m sorry. “I don’t think I’ve been as sorry about anything in my whole life.”