It's a mix of lack of perspective and bias. For folks whose metabolism and willpower work fine, shedding post-holiday pounds or fitting back into that outfit is effortless. They assume what's easy for them is easy for all (bias), so they lack compassion for those struggling (gap).
Still pretty fresh to this medication, only 4 weeks deep. Haven't stepped on the scale yet but the changes in how my clothes fit are obvious already. The puffiness has pretty much vanished.