So they're not a danger to themselves.
So maybe they can rehabilitate.
So they can think about what they are going to do and maybe decide not to.
Here's some information from a website:
"It is estimated that around 1 million people commit suicide every year worldwide. In a typical year, this is larger than the number of people who die through murder and war.
The most common method of committing suicide involves ingesting pesticides. Many suicides are committed by farmers in less-developed nations and they often use pesticides which were intended for use on their crops. Over one quarter of all suicides in the world are committed in this way.
Globally, around 16 in every 100,000 people commit suicide each year. By nation, the highest suicide rates are found in countries in the Baltic region. It is generally thought that, for every successful suicide attempt, somewhere between 10 and 50 unsuccessful attempts are made and one Australian study found that as much as 3% of the population contemplates suicide each week. In total, suicide accounts for 2% of all reported deaths though its incidence is believed to be under-reported. "
You could use that and say that if you hospitalized people who are suicidal you might reduce the number to 8 in every 100,000 or something similar.