Possibly by right wing conservative conspiracy theorists. There was a line on the stones advising that we should keep the planet's population capped at 500 million... to be sustainable with the environment obviously. That is heresy to the likes of Marjorie Taylor Greene. So it was blown up. "A mysterious monument in Georgia has been vandalized in a pre-dawn explosion. The Georgia Guidestones, which have been the subject of numerous conspiracy theories, constitute a 19ft-tall granite monument privately funded and erected by anonymous patrons in 1980. The stones are inscribed with what some people interpret as guidelines for future generations and others see as something more sinister." - THE GUARDIAN
From Wikipedia: Interpretations One interpretation of the stones is that they described the basic concepts required to rebuild a devastated civilization.[1] Author Brad Meltzer notes that the stones were built in 1979 at the height of the Cold War, and thus argues that they may have been intended as a message to the possible survivors of a nuclear World War III. The engraved suggestion to keep humanity's population below 500 million could have been made under the assumption that war had already reduced humanity below this number.[17] Yoko Ono said the inscribed messages were "a stirring call to rational thinking".[1] Conspiracy theories The guidestones became a subject of interest for conspiracy theorists. Wired stated that unspecified opponents have labeled them as the "Ten Commandments of the Antichrist".[1] Some conservative Christians have called the monument satanic.[15] Right-wing activist Mark Dice demanded that the guidestones "be smashed into a million pieces, and then the rubble used for a construction project",[18] claiming that the guidestones are of "a deep Satanic origin", and that R. C. Christian belongs to "a Luciferian secret society" related to the New World Order.[1] At the unveiling of the monument, a local minister proclaimed that he believed the monument was "for sun worshipers, for cult worship and for devil worship".[19] None of these critics provided any evidence of their claims.[1][18][19] Conspiracy theorist Jay Weidner has said that the pseudonym of the man who commissioned the stones – "R. C. Christian" – resembles Rose Cross Christian, or Christian Rosenkreuz, the founder of the Rosicrucian Order.[1] The guidestones were featured extensively in a 2012 episode of Mysteries at the Museum, a "Monumental Mysteries Special" featuring Don Wildman.[20]
Guidestone languages Below the two columns of text were written the caption "GUIDESTONE LANGUAGES", with a diagram of the granite slab layout beneath it. The names of eight modern languages were inscribed along the long edges of the projecting rectangles, one per edge. Starting from due north and moving clockwise around so that the upper edge of the northeast rectangle was listed first, they were English, Spanish, Swahili, Hindi, Hebrew, Arabic, Chinese, and Russian. At the bottom center of the tablet was the following text: Additional information available at Elberton Granite Museum & Exhibit College Avenue Elberton, Georgia Astronomical features The four outer stones were oriented to mark the limits of the 18.6 year lunar declination cycle.[16] The center column featured a hole drilled at an angle from one side to the other, through which the North Star could be seen. The same pillar had a slot carved through it which was aligned with the Sun's solstices and equinoxes. A 7⁄8-in (22 mm) aperture in the capstone allowed a ray of sun to pass through at noon each day, shining a beam on the center stone indicating the day of the year.[1]
The attached article on The Georgia Guidestones pre-dates the vandalism by a few weeks. The ‘Stonehenge of America’ Still Has Visitors Asking, ‘What Is This Place?’
Those on the right seem always to take umbrage against any new idea / movement / liberal progression , cogent suggestions , anywhere , any time, that may benefit humanity in general , be of interest in specific ways or even hint that what is-- should change , then as sure as day follows night,all must steadfastly remain as is and has been. It's the difference between how liberal minds and conservative minds take in and / or react to change,IMO. Perhaps the difference between fear and fearlessness.