How would businesses negatively be affected by global peace?

Answer 1

The manufacturers of weapons, guidance systems, tanks, warplanes, soldiers' meals, equipment, etc. would no longer have this business. The government that buys these products is a very sure source of income.

Answer 2

Would it also be because since many people won't have jobs they won't be able to afford certain services.

Answer 3

Yes. That could also be true.