Contracts are great, and may even provide for some type of compensation or remedy if you know and you could prove that Microsoft was using the data they collect against their own customers, but good luck knowing/proving that.
If Microsoft uses the data they have to come up with competing products, or to time the release of their competing products, or to decide which stocks to buy or short, or to decide which companies to partner with or avoid, or which of your employees they should try to attract, or even to sell or leak privileged information to your competitors you'd never know about any of that without a whistleblower at Microsoft saying something, and that person's income and very comfortable lifestyle depends on them keeping their mouth shut. A whistleblower may also risk legal consequences themself if they ever come forward. Risking themselves, their future, and their family is asking a lot which is why whistleblowers are extremely rare.
That's part of the problem with surveillance capitalism. All the spying being done is to collect massive amounts of extremely valuable data, but very little of that data is used transparently. You simply can never know how the data being collected about you will be used against you, you can just be sure that it will be.
The reason companies are investing huge amounts of resources into collecting, storing, and analyzing every single scrap of data they can get their hands on is because doing so is making them money hand over fist. I doesn't matter if it's your data, or your company's data, they'll be using it in any and every way possible if they even suspect that doing so will give them an advantage or make them more money and their gains will almost always be at your expense.