Energy drinks don’t really give you energy, caffeine just blocks the neurotransmitter that sends the fatigue signal. That just means that it’ll keep being sent across the synapse until the caffeine dissipates and then you’re flooded with that fatigue neurotransmitter.
It seems that they’re really popular with manchildren since they’re an alternative to drinking coffee where they’re sweet without the bitterness of coffee. Personally I like coffee and tea more, but I’m also not fond of how nasty energy drinks can taste.