I believe our LORD is heightening the level of the coming deception and is using the statement "if it were possible even the elect could be deceived" to do so.
He isn't saying it is possible, but in essence if it were possible. Matthew 24:24
"So that even the elect (if it were possible) will be led into error. This was added for the purpose of exciting alarm, that believers may be more careful to be on their guard;" - John Calvin
if it were possible, they shall deceive the very elect. By whom we are to understand, not the choicest believers, or the persevering Christians: not but that such who are truly converted, are choice believers in Christ, and persevering Christians are undoubtedly the elect of God; but then the reason why they are elect, and why they are so called, is not because they are converted, are choice believers, and persevering Christians; but, on the contrary, the reason why they are converted, become true believers, and persevere to the end, is, because they are elected; conversion, faith, and perseverance being not the causes or conditions, but the fruits and effects of election: besides to talk of the final seduction of a persevering Christian, is a contradiction in terms. Such an interpretation of the phrase must be absurd and impertinent; for who knows not that a persevering Christian cannot be finally and totally deceived? But by the elect are meant, a select number of particular persons of Adam's posterity, whom God, of his sovereign goodwill and pleasure, without respect to their faith, holiness, and good works, has chosen, in Christ, before the foundation of the world, both to grace and glory: and to deceive these finally and totally, is impossible, as is here suggested; - John Gill
Notice that, though the elect may be powerfully tempted, they will repudiate and resist the attack and still remain loyal to their Lord. What a searching word is this!-“whom He did predestinate… them He also glorified,” Rom_8:30. They may be tempted, tried, almost deceived, but angels will bear them up in their hands and God will keep their feet. See Psa_91:12; 1Sa_2:9. - F. B. Meyer
If the elect were deceived it would contradict God's word.