I still consume caffeine and nicotine. I’ve found that my cognition is improved by them; in the case of nicotine, I might just as well have regular pauses from work, though.
Coffee and tobacco, however, contain a host of other psychoactives which tend to bring about an easily distracted, impulsive frame of mind.
So many impulse buys are connected to a craving for the bitter, MAO-inhibiting alkaloids in coffee and tobacco smoke… it’s good for the economy, but not for your bank roll.