http://mikegravel.org/why
"We're not asking for your vote, and we're not planning on contesting any primaries. We're seeking to reach 65,000 donors, qualify for the Democratic debates, and use that platform to issue a critique of American militarism, plutocracy, and inaction on climate.
[...]
After getting in the first two debates and issuing the all-important critique of our destructive American empire, Sen. Gravel would leave the race and endorse the frontrunner among progressive Democrats."
Our future leader is humble enough to let other Democrats/traitors think they have a chance for the throne.