I'm fully aware that service desk costs money (personal and time)
I don't think money is a problem here. They've recently donated quite a lot of money, and there's this:
Bisq is one and the only truly decentralized exchange which we often recommend to our customers without any greed feelings, since our primary goal is not to make money but to defend some cypherpunk ideas instead.
I'm fully aware that service desk costs money (personal and time), but a serious business should meet some reasonable SLAs, at minimum don't celebrate the art of silence. And frankly, a customer shouldn't need to guess why they have trouble to respond to tickets in a timely manner.
You can be reliable and trustworthy for years with your business but you can also drive loyal customers away quite fast.
When I contacted an unknown instant exchanger, they responded within hours. You can't compare Coinbase, I have much higher expectations from small businesses that are
personally active on Bitcointalk.
My guess, and that's just a guess: if you're in the privacy business, you can't easily hire people. You'll need to completely trust someone with access to your system. You can't just hire someone from Indeed.