Encouraging people to smoke at a concert encourages non-smokers to not attend.
Secondhand smoke is a real problem. If you want to get high, do so privately. If you absolutely must get high in a public place, do so in a way that doesn't involve combustion and the subsequent production of smoke that others must necessarily breathe - with or without their consent - if they wish to remain in the same area as you.
Inject, ingest, snort, absorb it through your skin via a DMSO laced slap patch, shove it up your ass, whatever the hell gets your rocks off, just don't force your drug (and the carcinogens produced by incomplete combustion) onto others by dispersing it in to the goddamn air.