The DHS funding being pumped into the forces have resulted in police being better battle-equipped than the average country's military and this has become a recruiting tool. Don't want to sign many years of your life away and probably get shipped out to a -stan where you have to deal with constant misery just to live out a military fantasy? Just go to a police academy for a couple months and you can cosplay all you want while with all the same toys in a "target rich environment".
The end result is we've created a recruiting pull that only finds the worst possible people for the job. It would be like HR only hiring people for a software company who picked computer science entirely because they heard it was high paying but somehow far far deadlier.
On the other hand, people who want to harm others, have a higher chance of joining the police force. (Not all police officers, but some.)