I don't understand why oracle is required everywhere

Is this also an impetuous trend in the industry? As far as I know, it is a very time-consuming task for a good database administrator to transform from other types of data to Oracle management.
Oracle Database administrators do not have a low price. Why are oracle users still familiar with Oracle?

According toArticle<Excellent article recommendation: Large SQL Server servers: scalability, availability, and manageability> I saw this article on Microsoft's website, I feel that the performance of SQL Server is indeed beyond the general understanding. Although this article is written by Microsoft itself, to some extent it may be unrealistic, I still think the performance of SQL Severl can fully meet the needs of most domestic enterprise projects.

I really don't understand it. It's strange that if SQL Server is used, the cost of maintenance is lower than that of oracle, I don't know why so many departments want to buy oracle ...........