Of course it was initially designed to kill (and wound) enemy soldiers albeit that is a narrow way to categorize the evolution of the army rifles and their use.
If you read up on the M1 and the progression to the M16 and beyond you will learn the bigger picture.
The "lets make more money" sounds like you are a bitter beatnik who has not done well with capitalism.
The M16 was originally developed as a replacement to the M1. Over time there were variations made and it morphed into more of a platform than a discrete rifle. Curiosity, ingenuity, and needs caused it to be adapted to other uses. The current weapon and all is variations, add-ons, options, etc. make it the most versatile weapons' platform. Hence its popularity.
Hunting
Target
Plinking
Competition
Collecting
Varmint control
Herd Protection
Tinkering
Home, Boat, and Business Defense
The overwhelming majority of owners are law abiding and use it for the above purposes. 4 whack jobs per year choose to use the weapon for heinous acts. Some percentage of criminals use it and other deadly weapons for nefarious purposes. No laws will stop them from getting these and other deadly weapons in there hands.