It’s sad that many among the Muslims today are celebrating something which wasn’t even celebrated by the one whose birthday is being celebrated today. Neither did his companions do nor did the righteous predecessors from the first three generations.
Also note that the same prophet (صلى الله عليه وسلم), gave us only two Eids to celebrate annually.
And the other issue is that the date was never confirmed except the day he was born. So 12th Rabi-ul- Awwal is just an assumption and speculation just like 25th December considered as date of birth of Prophet Jesus (عليه السلام).
Thus those who follow the Qur’an and Sunnah avoid it as it’s not an act from the salaf but an act started by those later who were deviated from the straight path. They only followed their vain desires for their own political gain..
Prophet has to be remembered every single day by deeds that needs to be done by a Muslim on daily basis. Coz we need to emulate him in order to please Allah.
So you cannot single out one day for the same act just like the modern western world which singles out one day for celebrating something every year!
May Allah protect us from the deviated ways and guide us to walk on the straight path.