Worst case if I submit my passport to an exchange?

[sheenshane]

Hotels store your data, like your passport, that's the law in most countries, each country has its own rules. Taken a copy of passport or other ID cards, makes perfect sense, as authorities want to know who stays in the hotels and if something is broken in the room, or you didn't pay your bill, or in the event, something happens to you, they can find out who you are. Some hotels also make a paper copy of your credit card, on top of the deposit they charge on your card  

Wait, but the crypto market exchanges aren't the same when you are renting hotels, submitting personal data like passport was a very risky in our own especially showing our passport as a requirement on passing KYC. They can possibly use our passport details to travel anywhere who wanted to use or it can be sold on the dark web and it might be using your identity to some criminals to migrate in other countries.

Just like on Gate.io exchange, I have an account there but I can't withdraw my fund. Before they did not require KYC, but now they implemented on it and the only required you to passed KYC is submitting your passport which is contradicting to my part. I prefer to let die my small amount on that exchange.

[tranthidung]

Bittrex has done some shady things in the past, the most recent one, they failed to do proper DD on their first IEO.

Small exchanges can become big ones, while big ones can become small ones. It is a simple fact from market selections over time. There is no exchanes or platforms can be a big or biggest one forever.
Good sites can become bad ones, and vice versa, so it is probability that users' identities on exchanges will be leaked someday for any type of reason.
Therefore, it is why we need to have multi-level of security method, from our registered emails (strong passwords, 2FA for email log-in), to exchanges' security methods (passwords, 2FA). Together, all of those security methods at different levels can have overal-combined good secured level for our accounts.
However, it is always bad ideas to accept KYC requirements of airdrops, bounties just to get coins, tokens, money from them.