i am running my own lightning node since some days/weeks and i closed one channel (first to practice, but also for other reasons) and the mutual closing transaction looked a lot like the screenshot posted above. well i paid not that much, but it also stated "overpaid by 20x". i need to figure out how to get the "starting fee" the other node will propose as soon as the two nodes enter the "negotiation phase". sorry this is a lightning network question and a little bit offtopic. but i think the theory about lightning node useres paying too much to close channels might be right, it happend to me now at least once 

i wouldn't call getting access to bitcoin you bought a service, okay it is a service, but not a service which you can use to say: look at me, i allow withdrawals of bitcoin you bought which aren't yours if you dont withdraw them - they earn probably most of their revenue with trading fees - imo it is "bad business" wanting to earn a profit with withrawal fees (not sure they do or want to do that - i am just replying to the quoted statement