Why aren't exchanges starting to run/operate their own Lightning nodes? The incentive is there.
I don't think they care about earning 0.2
BTC in several months, or 0.25% on withdrawing small transactions (they earn much more from the common 0.5 m
BTC withdrawal fee).
And beyond that there will be time & infrastructure costs.
Unlike most of us, since they will be a bit more concerned with security (I hope...) their node is not going to be run on an RPi that was sitting around or a VM on a random desktop machine that has enough power to do it.
Going to need hardware, someone who knows what they are doing, redundancy, etc.
Going to be tough to justify the cost vs. profit.
-Dave