Day in day out there are new projects requiring kyc from investors
Exchanges requiring kyc, for some in order to maximize your ability to withraw large sums of cryptocurrencies and some even before you can trade on the exchange
The bigger question is how safe are our kyc documents?
It depends to whom you submitted your KYC documents. If it is a new unknown exchange or a program, there is a high chance of the documents not being safe with them. Again, if it is a well known reputed institution or an exchange or a project, your documents will be safe but can not be guaranteed. I would suggest you to avoid those new exchanges/projects that requires you to submit KYC documents. There is a high chance they will sell your information after scamming you out.