I know plenty of smart people, and I'm intelligent as well. I'd like to believe I'd gain power by cult-godhood, seduction, etc, but I can't see my smart friends succeeding at a high rate in my mental model of how they would behave. That makes me reluctant to believe that I would have any better chance. Some of the comments sound cocky, and require much too many things to go right. If we were properly pessimistic...

That being said, a 21st century timetraveler has a significantly greater chance of winning than an average Roman, just not a good one.