Hard to see how this is "especially true" with stimulants, given they're the rare case of psychiatric meds you can get on and off safely at any time, and the bulk of the effects appear in hours to days after starting the treatment (and disappear just as fast after cessation). Contrast with e.g. depression treatment, where it takes a month or more before it's clear if the drug even works on you, and which of the bad side effects have a chance of eventually going away.
"Long-term positive" is impossible to know in individual, non-statistical sense, whether it's about stimulant medication, SSRIs, moving to another city, marrying, or starting a family - any of those is going to have cascading impacts on your entire life, and even if you think they're positive after a month/year, who knows, maybe few weeks from now you'll think they were negative. That (otherwise stupid) "Farmer's Son" story has a point here.