wasted effort

Translations
напрасные усилия
All his hard work turned out to be wasted effort.
Все его усердные труды оказались напрасными усилиями.
Definitions
Wasted effort refers to the time, energy, or resources expended on a task or activity that ultimately yields no beneficial results or outcomes, often due to poor planning, lack of direction, or unforeseen circumstances.
Words
effort

noun
усилие
wasted

adjective
потраченный