Some do that.
Others like John MacArthur will say that if you stray from Christ 25 years from today -- then you were never saved to start with
1 John 2:19
They went out from us, but they were not of us; for if they had been of us, they would have continued with us. But they went out, that it might become plain that they all are not of us.
Hebrews 10:39
36 You need to persevere so that when you have done the will of God, you will receive what he has promised. 37 For,
“In just a little while,
he who is coming will come
and will not delay.”[
f]
38 And,
“But my righteous[
g] one will live by faith.
And I take no pleasure
in the one who shrinks back.”[
h]
39 But we do not belong to those who shrink back and are destroyed, but to those who have faith and are saved.
John 10:28
"And I give to them eternal life; and they shall never perish, neither shall any man pluck them out of my hand."
Hebrews 6:4-6
4 For it is impossible for those who were once enlightened, and have tasted of the heavenly gift, and were made partakers of the Holy Ghost, 5 And have tasted the good word of God, and the powers of the world to come, 6 If they shall fall away, to renew them again unto repentance; seeing they crucify to themselves the Son of God afresh, and put him to an open shame.
Romans 8:29-30
“For those God foreknew he also predestined to be conformed to the likeness of his Son, that he might be the firstborn among many brothers. And those he predestined, he also called; those he called, he also justified; those he justified, he also glorified.”