Why なくなる not なくなった


This question is about understanding なくなる here. From my understanding なる is an
instantaneous verb (not sure the term) so if なくなった was used it would imply
they have lost their confidence. But if they use なくなる then does that just mean
"I'm going to lose my self confidence" or something like "I've lost some of my
confidence".

> 「そんなにお強いのですか」
>
> 「稽古にならないぐらいに強かった。はっきり言って自分の自信が **なくなる** 」




This なくなる is a "generic" description that is true in the present and the
future, not a description of a certain event in the past. So something like
"He/She makes me lose my confidence" is close.

