Yes, they care, although the exchange arrangement is the one I know that takes risk for their client the most since I started online dealings. If it were to be other companies, you may not be able to hold $1,000 with them without duly proving the source of your funds. However, exchanges may tolerate some amount but when it is getting to a certain volume, they might tell you to proof the funds, especially if the KYT (Know Your Transaction) doesn't favour the person or it can't easily be implemented. But they may not have issues with you if you move out $1m from a well-known company's account. However, if it is suspicious, your account may be frozen for you to prove the funds.