They say no company has ever raised the kind of money OpenAI has, like they are at some kind of ceiling. Microsoft’s market cap, which is only equity, not including bonds (only $42B), is over $3T.
Also, I'd like to point out that the total investment into AT&T, which they position as untenable, is less than AT&T has spent on their network investments every single year for at least the last 10 years. It isn't like companies don't invest billions of dollars into things.
I do not THINK Microsoft will put that much money into it. They could! It isn't impossible. But it would be totally unprecedented.