[HPsquared]

It really depends on the environmental conditions. In the case of a deep sea submersible you might expect that the controller will always be in controlled indoor conditions, depending on when/where they open the hatch. In normal operation it's going to be dry, and if there's a leak the controller probably isn't going to be of much use anyway. (same goes with the rest of the electronics).

A car is of course much different, most components have to operate for years without maintenance in a very uncontrolled, varied set of environments.

[ansible]

Salty sea air and sea spray are all around you on a ocean-going ship. I'm sure they weren't intentionally dunking the Logitech controller into sea water, but that doesn't mean that it couldn't possibly be effected by the environment.

https://pomametals.com/salt-air-inland-distance-for-metal/

The Logitech controller isn't sealed for moisture. A single drop of sea water on it can slide inside and start the corrosion process. It looks fine on the outside, because the plastic isn't as affected.

Most of the buttons on a commercial grade PC input device use conductive carbon pads pressing against bare metal contacts on a PCB. Yes, the contacts may be gold plated, but there is still exposed copper on the sides.

Heck, even ordinary contamination from skin oil has caused one my keyboard's keys to stop working. I was able to take the keyboard apart and clean it, fixing the problem. The keyboard was never exposed to anything beyond a normal office environment, and never had liquid spilled on it.

Marine grade switches are waterproof and dustproof:

https://newwiremarine.com/marine-grade-switches/

If you take care and seal the soldered wires to the switch electrical contacts, it should be good for years and years of use, even at sea.