Microsoft didn’t innovate chatGPT, it bought openAI which pioneered the machine learning that enabled chatGPT. Basically it stole a march on Google which is why Google was in such a panic, they prematurely released their own chat or which failed spectacularl.Microsoft itself is a big dominant "monopoly". It so happens that microsoft has been doing better than google in recent AI software. Microsoft has their own search engine software competing against google, in addition to their Windows, Office, gaming and cloud software etc. All these various products have allowed microsoft to remain competitive.
These American companies didn’t innovate by themselves per se, they pulled a faceberg and bought out competitors.