It would not be an understatement to say that Bloomberg is THE global information broker for the financial sector - no one else has the same amount of data and analysis that they do. The Bloomberg Terminal is the defacto tool used by financial professionals globally, involved in moving trillions of dollars in assets every day. The amount of information hosted there is incredible: split second latest numbers for just about every financial and economic metric on the planet along with historicals going back decades, news before even news orgs start reporting out, proprietary intelligence and analysis that provide details into the supply chains of individual firms that the firms may not even have as clear of a view on, etc. They have a massive network effect advantage - their internal chat system has networked just about every major financial professional on the planet. There is also a regulatory advantage - the terminal is setup to navigate the complex web of financial regulations across dozens, if not hundreds, of regulatory bodies from a compliance perspective.
They are the defacto tool not just because they bring that data together in a way no one else on the market has, but it has a level of vetting, security, and support for a system that you'd expect for a tool that the entire financial sector depends upon. AI could do some of the data manipulation, but it would take years to negotiate access to the sheer number of proprietary data sets they have access to and find professionals to train the models.