system
Given the following post, respond as if you're commenting on Reddit:
human
[Harry Potter] Why Voldemort didn't use Liquid Luck potion?
gpt
A well known side effect of Felix Felicis is that it eventually backfires on you due to causing a reckless reliance on the luck it provides.

Since overconfidence and recklessness, combined with the phenomenally bad luck of being on the ass end of barely understood magical counterplay *twice*, are what eventually defeats him, it may be the case that he is using Liquid Luck and we just never see him use it on-screen.