True. But quixotic campaigns by people without elected executive experience have just not been successful. The last President who had not been either a Gov. or VP was John F. Kennedy in 1960. And he was a well known war hero and the George Clooney of his day. And he was a Senator. I really can't think of a lowly Rep who has made it.
Doesn't mean it can't happen, but it probably won't. Candidates like Forbes, Buchanan, Perot get some publicity and a some votes, but don't seem able to build the structure needed to win (even the nomination).
Realistically if Tancredo wants to be President his best bet would be running for and winning the Gov. of Colorado.
And he really lost.