Sign a message using the private key for the address 1MDq7zyLw6oKichbFiDDZ3aaK59byc6CT8 in order to prove you own it.
Or, you are a scammer.
Here proof
https://imgur.com/27sYlMiIt does not prove anything, sign a message is the valid proof that you owns the address which contains of 9,000k BTC
Most of transactions to above address were made last year. Why you did not sell it since the first big transaction?