"These are they who purchase this present life at the price of that which is to come: their torment shall not be lightened, neither shall be helped." (2: 80.)
For a better understanding of this verse, the context must be seen.
[002:079] Then woe to those who write the Book with their own hands, and then say:"This is from God," to traffic with it for miserable price!- Woe to them for what their hands do write, and for the gain they make thereby.
[002:080] And they say: "The Fire shall not touch us but for a few numbered days:" Say: "Have ye taken a promise from God, for He never breaks His promise? or is it that ye say of God what ye do not know?"
[002:081] Nay, those who seek gain in evil, and are girt round by their sins,- they are companions of the Fire: Therein shall they abide (For ever).
Purchasing this life here refers to what has been explained in the verses above and not what the writer argues. This is simple common sense. This is the most basic rule of reading in context and breaking this rule indicates either complete stupidity or deliberate trickery.