The writer might expect readers to recognize "Better to reign in Hell than serve in Heav'n" as a famous quotation from "Paradise Lost," by John Milton.
The writer uses it to mean that freedom is better than comfort, and that we should never seek comfort at the cost of freedom.
That wasn't what Milton meant, though. In Milton these are the words of Satan (the Devil, the evil archenemy of God... possibly like Iblis?). Since Satan is saying it, it is wrong! Satan is saying that it is better to be free than to serve God.
"Paradise Lost" is considered a major classic of English literature--but it is one of those classics that almost nobody reads. (The only person I know who has actually read it was an English major in college and read it as part of her studies). I've never read it and don't plan to, but I know the quotation.
LIke Dante's "Divine Comedy," "Paradise Lost" has shaped our ideas of heaven, hell, and Satan. Many things that people think are in the Bible are really from "Paradise Lost."
In "Paradise Lost," Satan is a former angel who rebels against God and is punished by being cast into hell. Satan is saying that freedom is more important to him than anything else; he would rather pursue his personal wishes than serve God.
"...Here at least
We shall be free; th' Almighty hath not built
Here for his envy, will not drive us hence:
Here we may reign secure, and in my choyce
To reign is worth ambition though in Hell:
Better to reign in Hell, then serve in Heav'n."