The popularity of Botox is mostly due to the fact that it really does work.
I am also fascinated by how its effect over time is cumulative meaning that the lines/wrinkles often never return to how they were before Botox was started even when the Botox has worn off. These photos show a case which demonstrates this. On the left photo, taken at the very first visit to the clinic, we see the frown prior to any Botox treatment. Botox was subsequently done 4 times at 4 monthly intervals approximately. The photo on the right shows the frown 18 months later is much reduced compared to the first photo even though it has been 4 months since the last Botox treatment.