I'd like to just make a point (I haven't read your whole post because I'm watching the game but this one jumped out at me).
In Canada, we have Universal Health Care and yet mental health services are very expensive. Canada is a country with 30 M people and a relatively strong economy. Tell me how you would put that solution on a country with 300 M people?
Might have been a security guard who thought there was something going on outside? Remember that there was gunfire outside before it moves into the club.
And how do you plan on doing that? This guy was born in New York and probably got radicalized by watching ISIS propaganda on the internet. Be realistic.
The only thing that can be done is removing the propaganda off the internet which is easier said than done.
Getting rid of the security guard who passed background checks loophole.
This is something we will live it. It is the war of our time. There is no real solution aside from going full Israel with armed soldiers everywhere and hoping that you're not at the wrong place at the wrong time.
Why was he under investigation? Was he visiting websites or was he communicating directly with people of interest? If it's the former, then what method of deterrence do you propose?
If the person you are referring didn't communicate with anyone about this attack, then how will surveillance change that? There are blind spots as there will always be.
Right now you sound just as dumb as the rest of the idiots here who just come out with their agenda without waiting for all the information.