Preaching something new (or forgotten) can be an overwhelming task. This is especially true for the Prophets and Messengers (peace be upon them all). After all, what they preached was something that would radically change the fabrics of the society. It was so simple yet so fundamental that people would understand it, but refuse to accept it because of its consequences. It changes the way people would view the world. That God is one and worship Him, obey Him.
Thus, the Prophets and Messengers (peace be upon them all) had oppositions. Usually the rich and the powerful would oppose. Sometimes the whole nation would oppose, leave a few who accept the message. Those who oppose would use character assassination to distract people from the message itself. These opponents would call the Prophets and Messengers as magicians, poets, and even worse, they would call them crazy. While in truth, these Prophets and Messengers are from their own people. And the people always knew they were upright, truthful and just. Having better character than everyone else in the society.
This was also the case for the Prophet Muhammad (peace and blessings be upon him). He was given the name Al Amin, the truthful, and everyone knew about his noble character. But when he started spreading God’s word, his opposition called him crazy. But, God gave the Prophet consolation. Reassuring him that he is not. In fact, God revealed that for the Prophet, there is endless praise. It may not have made sense for the opposition at the time, but it sure makes sense now.
After more than one and a half millennia, the Prophet (pbuh) is indeed praised without end. There is no human being on earth that is praised more than him (pbuh). Now there are 2.1 billion Muslims all around the world. And all of them (well most of them) when being recited the name of the Prophet will say “Shallallahu ‘alaihi wa salam”, may God honor him and grant him peace. Muslims praise him in their daily prayers, and because of the time difference between different regions, it is most likely that there is always a Muslim praying somewhere, praising him while doing so. And Muslims all around the world, not even ever meeting him, would burst to tears when remembering him, and long to meet him.
What God has promised is the truth. And no, he (peace and blessings be upon him) is not what they said he was (crazy).