If an average person got a huge windfall, that would raise a lot of attention, and people would wonder how they got the money. Police use sudden unexplained riches as a way to watch out for criminal activity, and everyone who knew the receiver of the windfall would ask questions. Between $10M and the other option, it may be easier to kill them with killing.
Agencies routinely set up fake businesses for cover, with the cooperation of insiders at big names (e.g. Dell). So you set up a fake SaaS, have your big name client buy the big thing 25k / CPU x however many you need to reach payout, done. All legitimized by a fancy public stock name.
If things really get too hot, it's easy to send a letter to any country's IRS via their local intell agency.
You'd be surprised how simple it is to close files in this world. I'd suggest reading Snowden's autobiography, Permanent Record. Very eye-opening and a great read.
