Can't be overestimated/can't be underestimated British negative speaking verb informal
There has always been some misunderstanding in using of the negative form in the expressions 'can't be over/underestimated'. Also, the fact that, when you use either phrase, the context of what you are saying usually makes your meaning clear.
An easy way to get this right is to remember the reason things can't be overestimated is because they are big/important and the reason they can't be underestimated is because they are small/insignificant.
Tiktok’s influence in the world of social media cannot be overestimated.”
Jake cannot be overestimated by her brother and entrusted his important files to her for safekeeping.
Private school education cannot be underestimated in comparison with the state-run public schools.
Used in response to a threat suggesting that the threat is a weak one.
To underestimate someone, something or oneself
To have low respect or regard for someone or something; To evaluate someone or something with a negative attitude
Completely developed, trained or qualified
1. To consider something as true, real or available without questioning it
2. To fail to show proper appreciation or gratitude to someone or something; to underestimate the value of someone or something
The combination of prefix over / under with verb estimate first found in 1825.