system
Given the following post, respond as if you're commenting on Reddit:
human
[harry potter] why didn't Voldemort install an alarm system to warn you whenever someone came near your horcruxes?

 

in book 6, we have the following statement:

>Lord Voldemort would not want to...immediately kill the person who reached this island," Dumbledore corrected himself. "He would want to keep them alive long enough to find out how they managed to penetrate so far through his defenses and, most importantly of all, why they were so intent upon emptying the basin.

if what Dumbledore says is true (which is in most cases) then voldemort has already considered the possibility of someone finding out about his horcruxes and destroying them. so why didn't voldemort install an alarm system?

bonus: if dumbledore is right, then that would help explain why voldemort wanted an heir, he has already considered the possibility that he might die (even if the probability is very remote)
gpt
For that horcrux specifically, he likely did. However, he's also arrogant enough to assume that nobody could possibly retrieve the horcrux and escape, so he probably just figured he'd check up on the fool who dared to oppose him at his earliest convenience. Voldemort's defining flaw was his arrogance and it's pretty safe to say that it is to blame for most, if not all, of the mistakes he makes in the books.