I think it happens a lot more often than you think, and current news reporting also skews the perspective one get.

Linked from another comment: https://blog.telegeography.com/what-happens-when-submarine-c...

> Cable faults are common. On average, there are over 100 each year. [...] Unintentional damage from fishing vessels and ships dragging anchors account for two-thirds of all cable faults.

100 each year would be one every three days, but of course you don't read about all them in the news.

I'm not saying none of the cable breakages are sabotage, I/we don't know. As far as we know, I don't think we have any cases (with or without confession) where we can be 100% it's intentional, at least yet.