Who would run a slasher and why?

As far as I can see there is no incentive to run a slasher; i.e., whistleblower_index is set to ‘none’ here - hasn’t changed since Altair as far as i can see.

That said, slashable offences have been caught (looks like about 224 so far - Validator Slashings - Open Source Ethereum Blockchain Explorer - beaconcha.in - 2023) - so folks are running slashers in spite of this (*assuming slashers are needed to catch slashable offences, but I could be wrong here).

So my best guess is that some entities are performing this as a kind of public service.

Wondering if there is a way to determine how many slashers are being run and if there has been any thinking done on this, i.e., what happens if everyone decided to stop running them?

I have a few thoughts on this, as the security of bridges will also eventually rest on the slashing protocol.

Slashers shouldn’t be limited to the active validator set allowing anyone report a slashable offence.
Slashable offence reports should also be rewarded thereby strengthening the security of cross-domain bridges

See linked post: Byzantine Fault Tolerant Bridges