The threat landscape is constantly evolving. The skillsets and techniques used by adversaries constantly evolve in terms of sophistication and efficacy. There's an arms race going on, and offensive capabilities tend to be outstripping defensive controls.
Some ubiquitous threat actors, such as those criminal gangs running ransomware operations, may not care too much about what data you have within your network. Most organisations are targeted by a range of threat actors, however, and some may be highly driven to gain access to your assets.