Revelation 6:16 And said to the mountains and rocks, Fall on us, and hide us from the face of him that sitteth on the throne, and from the wrath of the Lamb: 17 For the great day of his wrath is come; and who shall be able to stand?
They already acknowledge at the sixth seal that the wrath has come. By that time the kings and princes even had come to realize it wasn't just the weather causing bad things but it was God. You can surely know that they didn't admit at the first seal that it was God. These were unbelievers in the one try God after all.
“They already acknowledge at the sixth seal that the wrath has come.”
Not quite. They say “the great day of his wrath is come”. Firstly, the great day of wrath is a singular event, prophesied of in many places in the Bible, so we have no excuse to mistake it for some long, drawn out, years-long event. Secondly, “is come” doesn’t mean the same thing as “has come”. “Is come” can mean the same as “is upon us”, or “is imminent”, referring to a future event that must take place shortly. The future tense of this phrase is confirmed by the next phrase, also in the future tense: “who shall be able to stand?”