He's not polling at 10%, the responses to the polls are butthurt Cruzers & Sanders supporters. No way he gets 10% in November if Perot couldnt get 10% in 1996 against consumate insider Dole on a red meat issue. This is not a realistic poll for November.
No way Johnson does as good as family man Ron Paul, in GOP circles, as Johnson would do, in general circles.
Same with these other ridiculous polls months ago with 30 or 40% of Republicans jumping ship.
Johnsonite tried & failed against 2 totally committed insiders Romney & Obama. He got 1% in an election that actually turned out to be irrelevant in terms of SCOTUS & other things. The idea that he will do tenfold against Trump compared to R-Money, Romneycare-instituted, has little evidence.
There's an actual choice. Clinton will result in Campaign finance Super PAC changes with a SCOTUS pick. Trump will result in trade wars and different strategies for GOP to win as a national party. Trump will also be a celebrity president that has never been seen before. Trump will also incite a real hatred for the media & Congress that they really deserve.
If 5-15% of 25 year old white males anecdotally, like Gary Johnson on facebook or reddit, it is much lower with every other demographic who votes in November.