That is an extremely limited point of view.
First of all, that does nothing to disprove my point. Second of all, that comic is in a state of canon-limbo. In any case, the spirits of the dead can linger in the Fade, but there is nothing that indicates they can remain there indifinitely. Quite the contrary actually.
"What is this, a rebellious minion, an escaped SLAVE?" Yes... Yes it does. And there is NOTHING at all, that indicates what it offers would last forever. But it would surely use that word to trick gullible fools into a deal with it... And you still havn't answered why you are so quick to trust a Demon that would leech of your lifeforce, and would have absolutely no reason to keep its end of the bargain once it has you ensnared.
That is my Point of View, which I regard as realistic.
Show where the Canon of that Comic is put to Doubt. There is no proof that they can not linger indefinitely. Like I said, it is only Belief that the Spirits carry on and where they are going. We do not know what happens to them.
I am quick to trust that Demon because it seems genuine in it's Offer, as it has shown to put the Warden and the Companions in Illusionary Worlds, where they were happy, even though these Worlds are imperfect. It has also said, that it is able to make these Worlds better and provide happiness for Eternity. I am a Perosn, that always takes the easy Road. Maybe I am gullible, but just as I believe, that Demons are not inherently bad (for example, look at that Templar and the Desire Demon right before you encounter Sloth: That Templar was alive and happy, while the Demon got what it wanted and had no Ambition to harm anyone that didn't pose a Threat) I believe, that Demons like Sloth could be honorable in Terms of keeping their Promises.
There's actually a philosophy question surrounding what's being debated here. It's usually called something like the "pleasure machine" or the "happiness box" - basically, if we had amazing virtual reality tech and could simulate a wonderful, fulfilling existence, would you abandon real life to do that?
Yup, we are basically debating the Possibility of such a Thing via demonic Magic in the Dragon Age Universe.
But, regardless of the Universe, I would totally abandon Real Life to do that. It's not that my Real Life sucks, it's just that such a Machine would certainly make it better. Why bother with a normal Life, when you can have Perfection?