People who are convinced that they have high capabilities tend to be biased and make bad judgements.
They also don't see the bigger picture of things.
ご質問ありがとうございます。
"People who are convinced that they have high capabilities"＝「自分には高い能力があると信じている人々は」
"tend to be biased"＝「偏見になりがちで」
"and make bad judgements."＝「誤った判断をする。」
"They also don't see the bigger picture of things."＝「そして、広い視野を持っていない。」
ご参考までに。
アメリカ合衆国 
