What symbolize the 10 crowns (or diadems) ?
Revelation 13:1


And I stood upon the sand of the sea, and saw a beast rise up out of the sea, having seven heads and ten horns, and upon his horns ten crowns, and upon his heads the name of blasphemy.

Revelation 13:1 - King James



⚪ The papacy ruled not directly, but through other powers

Rev. 13 [...]
And upon his horns ten crowns. — In this calculation are included the three potential races plucked up to make way for the papacy. (Rev. 12:3; 17:3, 9.) In this picture the location of the crowns upon the horns instead of upon the heads, as in Rev. 12:3, denotes the changed situation after the papacy came into control. The papacy ruled not directly, as did Pagan Rome, but through other powers to which it was joined.

Source : 🇺🇸 1917 - Studies in the Scriptures, Vol 7, The finished mystery, page 194 + Cover


⚫ The world powers have used cruel force and violence to rule the people

This "wild beast" had "ten horns, and upon his horns ten crowns". Symbolically this means that Satan's organization on earth, and each kingdom taking the lead or preeminence therein in order named, has had and exercised full secular power to crowd and push the peoples of earth. [...] It is a well-known fact that these beastly governments of earth, which are Satan's organization, have horned and pushed the people about as a wild bull shoves aside the herd.
By their horns or power cruelly exercised these nations have pushed and oppressed the people; but they have particularly shoved about and persecuted God's people. [...] The crowns or diadems were upon the horns, thus symbolizing that these world powers have used cruel force and violence to rule the people and to carryon a conquest for wealth and territory and have always claimed that they did so by divine authority. They have made force or might what they call right. All wars of conquest and butchery they have justified because they claim it to be right and within the scope of their authority.

Source : 🇺🇸 1930 - Light, Vol 2, page 266, page 267 + Cover