台下一片沉寂，因为这个数字太不现实了。

Silence fell on the audience, because that figure seemed so improbable.

youdao

你本来有一个好机会，可是你太不现实了，现在必须自食其果了。

You had a good chance, but you proved to be unrealistic. Now you must lie on the bed you have made.

youdao

我们总是认为，有人雇佣便有了足够的安全感，但这几年我们也看到了，这样的想法太不现实。

We seem to think that being employed provides us with the ultimate security, but as we've seen in the last few years, that's more fiction than reality.

youdao

I think it's kinda...you do it to both but right now, tax increase in 2011, 2012, 2013, etc. as what's on the books would be very bad for the economy.

双管齐下当然不太现实,但目前来看，要是从2011年开始，按照经济理论，而一直往后增税的话,对经济可谓百害而无一利。

斯坦福公开课 - 经济学课程节选

You could use the "I want to" pattern to express something much less practical as well.

你也可以用“I want to”句型来表达不太现实的事情。

I want to 课堂 - SpeakingMax英语口语达人