'overestimated him' is correct and usable in written English.
It can be used to describe a situation in which someone has judged another person to be more capable or more important than they really are. For example, "I think you may have overestimated him; he isn't really qualified to lead the project."
But he worries that people overestimate him.
"Burying him there would be overestimating him and smacks of megalomania," he said.
We should not overestimate him; his excursions into the beyond will always lag behind those of his namesake Henry, who reminded Monty, when they met, in 1903, of "a respectable butler".
So, yes, there are bigots in the Trump movement, and wackos, and dummies, and sometimes I had to remind myself that the important constituency is the persuadable middle segment of his supporters, who are not finding in Trump a suitable vessel for their hate but are misunderstanding him or overestimating him, and moving in his direction out of a misplaced form of hope.
To judge from the stock in his company, WYNN RESORTS (67, WYNN), investors are overestimating him now as much as they underestimated him four years ago.
"Enzo has definitely been underestimated," said Wifey, overestimating him.
Lastly, I'll say this: I care very little to hear the same distorted slanderous far leftist ideology (such as calling him fascist) that helped get Trump elected in the first place by overestimating him.
Zuckerberg's influence can't be overestimated; he can recommend one title to the 30 million people who follow him.
Mr. Iconis, like many before him, has overestimated the entertainment value of listening to someone whine about his writer's block.
His intimates nicknamed him "Slow .Custer also overestimated the stamina and hardiness of his troops.
