Raise taxes, educate therapists, psychologists and psychiatrists, pass laws and guidelines concerning mandatory treatment, build institutions to house people determined to be a danger to themselves and others. Pay for it publically.
But that would potentially trample on people's rights (forcing treatment) and socialism (using taxes to pay for it) is always bad, right?
We used to have state run asylums. They weren't always nice places and sometimes they were hell on earth, so we got rid of them and didn't replace that system with anything. We just pushed the people who needed help out onto the street to fend for themselves. and back on families ill-equipped to handle their loved ones.