有冇問題呢句野

我估你係想話"接受唔到失敗嘅人就係失敗者", 係咪?

I would say:

For those who cannot accept failure is absolutely a loser

The person who cannot accept loss is absolutely the loser

That is a pretty good sentence. But there is another one fits it:
Loser never learnt from mistakes in the past.