False accusations made by people

Uqba ibn Amir (RadhiAllahu Ta'ala Anhu) reports that the Prophet (peace and blessings be upon him) left one day and prayed for the martyrs of Uhud.
Then he returned to the Minbar and said;
‘I am preceding you. And I am a witness (Shaheed) over you all. I
swear by Allah! I am verily looking at the Hawdh Kauthar now. And verily, I have been given the keys to the treasures of the earth, or
the keys to the earth. And verily, I swear by Allah! I do not fear that
you will commit Shirk after me. But I do fear you will compete and fight with one another.’

(Sahih al-Bukhari; Book of Funerals; Chapter; Prayer on a Martyr)

In short, if the Prophet (peace and blessings of Allah be upon him) did not fear his Ummah would commit polytheism after him, why do these narrow-minded people (who call themselves Muslims) think it is a problem of epidemic proportions?

Calling the Celebrations of Meelad un Nabi (SwallAllahu Alaihi Wa Sallam) and the Urs of the Awliya e Kiraam as "Shirk", Astagfirullah...

Do these people purport that –Allah forbid- the Prophet’s prediction and analysis was wrong and that they are
right? Do they think that they know and understand the religion of Allah better that the Beloved Prophet Peace and Blessings be Upon Him, who, in the words of this Hadith, has been given the keys to the treasures of the earth?