The two biggest problems in IT security today ...
... are the same as they have been for the over a third of a century I've been making money in the IT world, and probably go back to the dawn of time.
The first is convincing management to throw enough money (resources) at the problem to have the correct hardware for the situation ... AND the staff to run it properly.
The second is the big problem ... 90% of the userbase is incapable of wrapping their tiny collective hive mind around the concept of security.