"it's impossible to overdose or cause brain damage of any sort."

I really don't think that's true. Excitotoxicity is a distinct possibility. 5-HT2A and 2C agonists enhance glutamatergic currents. Glutamatergia involves calcium cation influx into neurons. Calcium cations promote the release of proteolytic enzymes - and other catabolic enzymes - which damage the cytoskeleton and destroy mitochondria releasing reactive oxygen species into the cytosol.