I do not know of people that would rather choose only what they need over what they want... Sometimes (often) both aren't mutually exclusive, we all need and want: to have food, shelter, survive, avoid pain/injuries/torture, self-esteem, etc. etc. They can be both needs and desires. Now I'd wonder, even if one had no desires but to fulfil his own needs, would the imperium still be a better option than chaos? For some maybe, but since there is no peace, only war, I'd rather be on the most likely winning side. The Imperium is, in the long run, just trying to patch things. As much as they hold...they are on the defensive. You don't win war on the defensive. We can say abaddon is a failure, but quite honestly, how many successful invasion of the warp against the chaos gods humanity had? Maybe if you are from a very rich and powerful nobility on some paradise world, chaos isn't for you. If you are one of the High lords of Terra, or some man of status and power who doesn't have to make any sacrifice, hard work, or worry about his own survival., again, chaos not good for you. I fail to see anything the Imperium could bring me that chaos couldn't even in the need department, and definately the imperium would never grant me any desire if I'm of low status and not an incredible prodigy at something. I'm unfortunaly a regular guy from a not rich family with no status and I'm not a great scientist nor a superb athlete or some kind of hero. I'd never get any recognition in the Imperium. I guess we could argue about morals and doing the right thing etc. etc. But there is no such thing as right and good. People die in droves for a yes or a no, no one cares about you, your life, your aspirations. You are a tool of some administration, a servant of a universe that doesn't care about your world, your name, your family, your loves. There is no moral in this universe, so doing the "right" thing isn't a thing in itself. EVEN if chaos would win, that doesn't mean humanity dies, it just means the imperium dies.
The endless possibilities of the warps creations, Obliterator virus, daemon possession/symbiosis, fusing into a machine and becoming the machine, even spawndom is a bonus. But the biggest attraction would have to be the freedom to kill anyone who was in my way or causing issues while at the same time being a target for others. A existence where your actions are what define you rather than words or pieces of paper or inheritance.
Because of what it has allowed us to become. The Emperor treated us as little more than rabid hounds, pets he could unleash upon his foes and put down when no longer needed, just like he did with his Thunder Warriors. Our father knew it well, and he would have none of it. We who were once dogs have now turned into holy warriors! No longer are we scolded and demonized for crushing our enemies in the glorious fields of combat, for manifesting the very essence of what it means to be a warrior, but blessed, and elevated into eternal life! Even in death, our ever-defiant souls are reborn as the mighty Neverborn, the true incarnations if the eternal warrior spirit! Our days of mindless butchery, of throwing our lives away in the name of a system which doesn't even care about us are finally over. For we now are paladins of the Blood God, anointed in blood and seething with a new purpose. To DROWN this galaxy, in an unstoppable tide of endless bloodshed, such is the will of Khorne! BLOOD FOR THE BLOOD GOD!!! SKULLS FOR THE SKULL THRONE!!! LET THE GALAXY BURN!!!!
no space marine was designed for be the ruler class in peace time: this is exactly why the emperor replaced thunder warriors, they was better fighter and easier to control, but he needed more than simple warriors for the grear crusade.
Because chaos is the fundamental truth to the WH40K universe, and one of the primary truths to our realspace material existence we call "life". Albeit in a slightly different sense on the latter part. Everything is chaos, or a byproduct of chaos. The Imperium is an illusory form of control and governance. It too will succumb to the scythe, when the hand of time deems it fit. All things will change. All things will ruin. All beings desire. Conflict will likely be eternal. These are inherent truths, especially so in WH40K. These are also base truths of chaos. Our flavor of chaos is dark and "evil" because the gestalt of the warp is fueled by unpleasant emotions that every sentient being with a warp connection contributes to. Yet the force of chaos itself is not evil. It is merely a reflection of the true inner psyche and thought forms of the collective sentience of an area, in our case the Milky Way. Chaos is what we would see looking back if we collectively all took a look in the mirror. If we were to change our thinking en masse, it could be the ultimate tool to transcend mortality, disease, and physical material limitations. See, the chaos gods essentially have the game figured out. They exist without physical bodies, only manifestations of their pure thought forms given physicality. They are entities that have transcended material limitations and evolved into a state of virtual godhood. What do they do all day? They organize grand plans, bicker, and basically fuck around with mortals because it appeases them and feeds them. Not a bad existence considering the lives of many mortals. The warp is a timeless place where multiple realities and ethereal limbs of what may have been, what could be, and what will never be all play into the same moment, then shift incessantly. Its the true realm of chaos, where anything can exist, all of it does in some sense, and at the same time, none of it is permanent or true, all is permitted. It is above duality, and not a viewpoint all beings can embrace, as many who experience the warp face insanity or madness from having their perceptions of reality altered through what they experience. The main reasons you should follow chaos is because it allows you to explore yourself, the world you live in, and the realities and possibilities beyond what you've been presented as truth your entire life. Especially in a 40k setting.
Like other people said Chaos isn't evil. It's just selfish. You can understand way Space Marines would turn to chaos. The only true evil race in 40k is Dark Eldar who are unapologeticly evil.
Everyone has a different reason to join Chaos. Some want power, revenge, freedom or anything else one can imagine. But once you commit yourself there is no turning back. You'll walk the road to Chaos as long as you live and even when you die your soul will belong to the Dark Gods. But in return, you will receive power and gifts most mortals can never conceive and fight for something that is tangible and real, instead of a hypocritical liar like the Emperor. In the end it is your humanity and free will, the very things the Emperor tried to take from you is what saves or damns you.
