Fritter away
Definition 1 of 1
Pro Tip 1/3Connotation of Loss
The phrase often implies regret over losing something valuable by not using it properly. 
I frittered away my time on social media instead of studying for exams.
Pro Tip 2/3Gradual Process
'Fritter away' suggests a slow, piecemeal process, not a sudden one. 
She didn't realize she was frittering away her savings with those small, frequent purchases.
Pro Tip 3/3Not Always Negative
Sometimes used in a light-hearted way to describe spending time on leisure activities. 
On the weekend, I like to fritter away a few hours gardening.