✔ 最佳答案
"due to" introduces an adjectival phrase, so it should only be used if you're qualifying "enemies". Since you are qualifying "made" you need an adverbial phrase starting "owing to". You can always get around this problem by using "because of" which qualifies the whole of the main sentence.
It's OK to use "usually" although "often" would read better. He made countless enemies because of his often tactless remarks.