Seen this same method applied to used equipment for sale, especially if it was stolen.
Basically, someone steals a laptop, wipes it, reinstalls the OS with backdoors, sells the laptop for cash, exploits backdoor access to own other devices, exploits owned devices, etc.
Take it one step further. Someone has a target that they are trying to acquire (company website access). So they run a fake contest where the prize is a laptop. The laptop that they ship to the "winner" is backdoored as you have described.
Right, hacker might even target a website that's known to be visited by the targets, hack it, use it for drive by downloads attacks - and use the contest win a backdoored device (laptop,iPad,drive,etc) to cherry pick any targets that have not been compromised.
Basically, someone steals a laptop, wipes it, reinstalls the OS with backdoors, sells the laptop for cash, exploits backdoor access to own other devices, exploits owned devices, etc.