Freedom from rules, authority, freedom to do what I want, even if the options of things to do are limited.
Everything you said was fine until I read this, then I just laughed. There is no such thing. Once you're a hobo, you're still bound by rules, authority, and liberty to act however you wish. Hobos can be denied entrance to stores if they're deemed so smelly that they repel customers, they can be arrested for lying down on public streets (an actual law in my city, a stupid law at that), they still require help from the community if they want to live.
You say you're fine with just dying or going to prison, how is that freedom? That's accepting the lack of freedom if anything else. It's known as being institutionalized in the prison industrial complex, so used to prison and unable to cope with society that you end up committing crimes simply to go back to prison. Being in prison, you're forced to follow a strict routine and being told what to do. Don't follow the rules and you'll be beaten, not only by the guards but by other prisoners. Since you supposedly don't care for authorities, the prisoners won't even worry about you reporting to the higher ups for help.
Now, on the subject of dying. How is that freedom? Liberty is the freedom to live. Certainly by dying you'd be released from the pressure of government and society, but you'd be leaving yourself to the fate of the unknown. Atheism is fine in that you believe there is no higher being, but the fact is that no human has ever given proof of what lies beyond. What if we simply go through a complex system of reincarnation, you'd be brought back to this shoddy world possibly worse of than you are now. There are infinite possible scenarios in the possible after-life. Even if there are no events after death, still how is that freedom? You would not be able to do what you want, you would be bound to the unmoving and unthinking state known as death. Slavery was bad in the sense that the people were forced to move as they were told, but to be unable to think is far scarier in my opinion.
There is no such thing as absolute freedom. The most freedom you can achieve is to be uber rich, and even then you're dependent on the amount of money you have. The sovereigns of the various countries are bound by the will of the people. Hobos are bound by the support of the government. Prisoners are mostly bound by the support of their fellow inmates. The average citizens are bound by their wages and society. Absolute freedom doesn't exist (unless you're a god).