They send transactions in a batch so definitely there's not much that they pay and I have seen them paying BTC0.00007 for transactions while taking BTC0.002 from each member who withdrew which is garbage in my eyes.
Do they batch transactions using legacy or SegWit format addresses? From the 7k satoshi fee you're stating it looks like SegWit to me, but it could also have been a batched legacy transaction sent without much network congestion.
If they use SegWit then it's absolutely ridiculous that they dare to ask so much in withdrawal fees. It's probably done so that people no longer withdraw their funds but keep it in their account and potentially trade more.
I have always believed that this exchange is largely insolvent. They have waves where people easily withdraw and waves where there are a lot of complaints popping up regarding withdrawals that aren't being processed.
The transactions I saw were not SegWit, but like baofeng told you they started using SegWit in late 2017 and continued using the same fee format they had been using since, but no matter what even if they ask it for legacy it is still unjustifiable on their end to give a reason why they had been stealing our funds through high fees even when, during current days, transactions are being confirmed at a fee of just 1 or 2 Sats/byte.
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I had 0.005 BTC lying there and thought of not withdrawing as it would take 0.0015 BTC as fee but when exchanges started getting hacked, I preferred paying the fee. Most of my coins there have been delisted or have no trading volume and they ask me to pay 300-400 tokens as fee which is way more than the tokens I hold there. I prefer Tidex as they still have a reasonable fee and even Kucoin.
They pay few sats per transaction which is why I had to use an accelerator to get it confirmed after 5 hours. After paying fee, they don't even use 10% of it.
That's the point I was trying to convey that these ridiculously high fees will get them their customers fly away from them to different options available. Even Binance doesn't ask for this high fees while comparatively giving much better services than hitbtc.