Crassus, Caesar's very close ally/friend, had just recently destroyed his own (fairly weak) reputation as a general and died fighting in Parthia. That had to be

Crassus, Caesar's very close ally/friend, had just recently destroyed his own (fairly weak) reputation as a general and died fighting in Parthia. That had to be on Caesar's mind because it was a major motivation for his own expedition. Caesar would have almost certainly done much better than Crassus, being a much better general. Still, it must have given him some pause, especially considering the unappealing style of warfare to be fought there which the Romans weren't well suited for. Caesar had by this time been at the very top of the social hierarchy in Rome for years. He had achieved his lifelong ambition of being considered one of the greatest Romans of all time. He had nothing left to prove to anyone. He was simply too smart not to have not considered the fact that that he had very little to gain and a lot to lose. My feeling is that his own health, a lack of strong motivation, and a concern about tainting his reputation would've added up to a desire for a glorious and early death by assassination.