Usually, large organizations have already invested a large number of resources in existing monolith applications that represent the core of their business.
According to Gartner research (Kurt Potter, Sanil Solanki, and Ken McGee, Run, Grow, and Transform the Business IT Spending: Approaches to Categorization and Interpretation, Gartner G00308477, June 27, 2016):
"The CIO of a company invests 70% of his budget to maintain the current portfolio, 19% to evolve the existing applications and only 11% to build new applications."
Besides, there are also some examples, such as the one described in The Majestic Monolith (https://m.signalvnoise.com/the-majestic-monolith-29166d022228), that demonstrate that a monolith application is not the devil like someone has said.
So, why tear down the monolith?
The response is always the same. In most cases...