If and when I ever forget where I came from, who I was, what I was like, etc before Jesus intervened in an unspeakable act of grace, then yes, the gospel can lose its wonder.
When I forget that I was aimless and wandering, the gospel loses its wonder.
When I think that I am good in and of myself, the gospel loses its wonder.
When I think I’ve earned everything I have (my job, my car, living situation, relationships, education opportunity, etc) then I make myself a god, de-emphasize the grace God has afforded to me, and the gospel loses its wonder.
When I forget I was rebellious and, as my siblings would tell you, a bit of a devil-child, and think I’ve always been serene and the “kind” person I am today (which is pretty spotty) the gospel loses its wonder because I neglect the fact that God had to give me a brand new nature to be like Him.
So yes, the Gospel can lose its wonder, but never rightfully so. It comes when I forget, and that’s why the Bible tells us to remember, to look to Jesus, to meditate on Him. It’s why Jesus is called the author and finisher of our faith. To leave any part of our salvation in our own hands (other than the part where we believe,) is a dangerous thing.