Short Sighted
When you are a company the size of MS with virtually unlimited money income. (MS is still a monopoly)
You can afford to lose a lot buying other companies:
You are sufficiently big and have enough employees and subsidiaries to make something clever and worthwhile with regards to taxation and regulations.
You spend a lot of money in exchange of a brand and a customer base and to lesser extend expertise, the customer base specially if the brand is strong is worth potentially way more than what you paid for the sum of the entire company you are buying. You have the new customer's base full attention, the best marketing ever.
If you succeed in conquering another large market and get entrenched, the benefits usually dwarf the costs. And you look mightier than ever.
Also with MS there is the "prepotency" factor.
MS is used to everybody being afraid of them and to use and abuse their power to further their goals.
Biting the hand that feeds IT
