He surely went off the deep end when he bought that restaurant.

他买下那家饭店的确太贸然行事了。

《新英汉大辞典》

It's all well and good to jump off the deep end if no one's depending on your earnings. But if you have a family or other dependents, you have to be absolutely sure before you strike out on your own.

如果没人靠你的收入生活，能跳出困境当然好，但是，如果你有家庭或其他依赖你的人，那你就必须在自主创业之前绝对有把握。

youdao

Tom went off the deep end when he heard the news.

汤姆听到这消息时勃然大怒。

youdao

"As with so much, the Bush administration has gone off the deep end, " Clinton said.

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Let's face it, some high-income taxpayers went a little crazy in recent years, and some tax advisers went clear off the deep end.

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Yet when you have Donald Trump defending your new policies, it is as glaring a sign as any that you have gone off the deep end.

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