> If we don't block the consumption of caffeine in youths, why should we block the consumption of nicotine - a compound with similar effects? i.e. Why is nicotine so much worse than THC, alcohol, caffeine, guarana, or any number of other stimulants/depressants?

Alcohol and THC are both already restricted to adults. Caffeine is restricted as well, in that many places won't sell caffeine pills to people under 18.

Nobody is talking about preventing kids from buying tomatoes. But when we're talking about concentrated and extracted forms of a stimulant... those are already heavily restricted.