Training is another cash cow from big tech, on many levels. It is a bonus for resellers and partners, binding the ecosystem together. And the maze of certifications that expire every other year or so makes big tech corps even more money, and has everybody invested. It is also a useful sales tool, because they don't cost much and can be thrown in as a discount. You can also achieve a kind of vendor lock in on the career skills more easily with certifications. Legions of Microsoft technicians are pretty much stuck in the ecosystem, because if they switch their certs and experience don't mean anything anymore. Not everybody has the technical chops to switch ecosystem every year. Even more pressure to not move to open source (or another vendor).

If you think Microsoft makes it sales because its buyers are putting the right product in the right place, then you haven't seen a lot of Microsoft sales. This is absolutely not how it works. And it doesn't have a lot to do with corruption either.

The people making the decision to buy an IT product are often not its users, and often not that much concerned with making the best short/mid/long term deal in the interest of the business. They are very much concerned in making the best deal for their own careers, and as these are the people who buy the thing some companies have competently specialized in optimizing sales given that fact. Oracle has a reputation for this, and Microsoft as well, but all big tech does it (just some do it better than others). Of course, there's some nuance, you can't get away with it if your product doesn't work.