The causes of rogue waves are not understood.

Is there a lot more to it than "random waves, it's less and less likely for them to overlap more and more, but sometimes that too happens"?

Wobble a glass of water just the right way and you will get rogue waves from constructive interference. The problem is predicting them in the ocean.

The problem to be understood is how you get a dozen waves constructively interfering over a long distance, not just popping up for a moment.

if a physics/acoustics class the professor set up a pair of speakers 30ft apart each playing a simple sine wave. The students then marched in front of the speakers, probably 50ft away, and as you walked you could clearly hear where the constructive and destructive interference was happening.