Maybe this could actually be someone who has long lost access to the wallet but just recently recovered it and decided to move the funds to a safer destination. It might just be an upgrade in wallet security since all funds are moved into a single address that does not belong to an exchange.
Most likely someone who wanted to sell some of his BTCs and keep some in another high-security storage. As we know, you really need to have some movement of your BTC in order to further secure it and not to give hackers any progress if they wanted to get your BTC by hacking the wallet you are using. By moving your BTC to another wallet, you are actually making a good move here because you are maximizing your security and also assuring that you have still full total control of your BTC despite holding it for more than a decade.