Also worth noting that the ‘season’ is only fourteen days long, at least by default. The remaining two and a half months of each season are abstracted out. So things happen a little more quickly in the game. Addictions come and go a little faster. It’s a little handwavie, admittedly, but y’know.
As to the performance-enhancing potential of stimulants, that is trickier. There is plenty of evidence that stimulants like methamphetamine and cocaine can have measurable positive influence on many cognitive tasks, including simple reaction time tests. However, under most - shall we say - ‘recreational’ conditions, the same drugs show a negative impact on these same tasks. Basically, there is a threshold upon which these drugs can provide benefit, and it is not an easy threshold to achieve or maintain.
I am not really in favor of modeling realistic drugs either. Drugs are complicated, unpredictable, have ‘stages’ with varying effects, and would take a lot of work just to make them undesirable given the game we’re playing. Cocaine use would probably get you killed in any kind of survival situation. It might make you feel like you’re faster, better, stronger, and on top of the world - but ultimately that’s just part of the high. And is liable to make you take risks that you are less prepared for than the drug effect is leading you to believe you are.
So yes, drugs are, by in large, fine the way they are. I wouldn’t mind seeing the addiction chance get a cumulative effect, starting low and getting higher the more often you use the drug over a period.