I doubt any American president has been invited to a royal family wedding. Do you happen to know of any? .... and it's not surprising other monarchs would attend, because they often marry their kids off to each other.
"To waste, to destroy, our natural resources, to skin and exhaust the land instead of using it so as to increase its usefulness, will result in undermining in the days of our children the very prosperity which we ought by rights to hand down to them."~ Theodore Roosevelt (Message to Congress, Dec. 3, 1907)