I am seriously thinking of commissioning a simple tungsten cube emblazoned with cuneiform style figures, set up on a stainless steel platform. For the legacy. For someone millions of years from now.
For wanting to leave a legacy that will last, and a message for anyone or anything that finds it? No, that's not insane, that's understandable, I think.
What will determine the insanity quotient is the message you want to inscribe.
"We finally deciphered the text on it. It's a monument to love, to undying loyalty and affection! How amazing! Here, it reads: 'Never gonna give you up, never gonna let you down'"
Parts of it remain indecipherable without the social context, however, as the writer explicitly assumes a mutual knowledge of some set of unspecified rules.
From the line "Never gonna run around and desert you" we can gather that when a relationship came to an end, the person ending the relationship would run around frantically and burn all possessions of their former partner, thus turning their property into a desert, or "deserting" them.
Can we all splurge on a cubesat with a vinyl record or some other media that contains "never gonna give you up" , and make our own voyager sattelite for other lifeforms to receive?
Thousands of years in the future, our descendents will return to Earth, to visit museums of ancient culture, and marvel at the Tungsten Cube of Dickbutt.
Oh boy is that going to be a perplexing mystery for future archeologists. I can already imagine a PhD student banging their head on a desk screaming: “none of this makes any sense”.