Because the fat dotard Orange Fraud is an inveterate liar, bigot, racist & slavish sycophant to anyone more megalomanic than he is. He HATES that Trudeau, listed as 6'2", is visibly taller than him in all photos, despite his claim to be 6'3". He hates that he has tiny hands, & this is easily shown in any photo of him shaking hands with Trudeau, who clearly has much larger hands. He hates that Trudeau is diplomatic, honest & relates positive, life-promoting ideals with his words while he offers only risible braggadocio & rude, infantile insults. He even hates that his country struggles with a National Debt that is $68,301 per capita while Canada's is but $14,037 per capita. Mostly, he hates that he knows he's been a life-long LOSER looked upon universally with contempt, whereas Trudeau is widely regarded as an effective leader & a gentleman.