The reason you see people selling fake traffic, is to increase their Alexa rankings with traffic. They are either looking to increasing sell their site in flippa, or just pretend they have a big dick to someone.
Also, 99% bounce rate, doesn't effect your website, UNLESS Google is directly sending the traffic that is at 99% bounce rate, or a search engine. Also, the only way Google can know you other stats is with Google Analytics... so if you are doing something shady that is attempting to fake your way up, it would be retarded to install Google Analytics...