Trump did not need to spend decades, which speaks volumes for his efficiency and analytical skills to bring forth a coalition very quickly. In fairness, he is living in a time with far more technological achievements than Ceasar. Ceasar did not get to have his words broadcasted on television throughout the Roman Empire. There was no internet, for example. If such things existed back then (but everything else was the same) there's no telling what would have happened. My estimation is it wouldn't have taken Ceasar nearly as long.
Well, firstly, I don't think that's sound reasoning. If somebody claims to have achieved something in a far shorter stretch of time than precedent would allow for, the properly sceptical response is to interrogate their claims, not to attribute to them super-human abilities. And, indeed, Trump's slapdash coalition hasn't made it past his first year in office, while Caesar's, in some form or another, outlived him by a century.
But, secondly and more importantly, it's really not a question of skill or technology. Robust alliances aren't just about a coincidence of belief or interest. They're build on established gave-and-take. Caesar's patronage network worked because it was based on well-established and well-tested relationships, its participants had spent decades deriving tangible benefits from it, decades of satisfied expectations. The network was
proven to work. Trump's coalition is people who, at their most optimistic, imagine they can put aside their enormous differences for the sake of the country, and at their most cynical, that they could take all the other guys for suckers. There's no proof of concept, there, Trump left that until he actually took over the administration, and it's almost immediately fallen to pieces. Trump talks about a movement, but he's put absolutely zero effort into movement-building.
