(1) because he is currently (I believe) the wealthiest man in the world
(2) because he uses that wealth to influence politics across the globe, from Germany and the UK to the United States
(3) that - and this is my opinion - this influence should be illegal
(4) that he has a long history of lying, overpromising, under delivering, not withstanding his other achievements
(5) that he is in bed with the current US administration which is doing a lot of damage inside the United States.
(6) that he personally took on roles in that government and did a lot of damage outside of the United States
(7) That he was very much a darling of the left leaning portion of society and used that position to enrich himself and then did a 180 and aligned himself directly and openly with various extreme right parties all over the world. Some people feel betrayed.
So Musk elicits a lot of emotions, for better or for worse.
Does that help?