What happens with the bitcoin after a few years, does their support siphon the coins?
From what I know they don't have access to any means to access users' coins. At least that's what they claim.
So the answer would be: the coins are lost forever(*)
Could be a big amount if there are thousands of users who lost their passwords, forgot that they have an account here, just two months ago I was searching on my folders and I found out I have another blockchain, info account I'm using for my airdrops, I opened it and discover I have 100k satoshi, how many users here that forgot about their account like me.