How detrimental is redlining in neutral (Manual Transmission vehicle)?

Yeah, i mean, who doesnt like to tell everyone that they are here via revving the engine in neutral. Anyways, i wanna know how bad im hurting my car when i do such. Start up, drive up to people or while waiting in traffic, rev up to 7000 rpm (red line) a few times to make noise and then drive normally. Also sometimes i do such maybe less like 5500 instead of honking the horn and saying hi to people as i p them.. yeah, thanks.