Does it make sense to do profiling for potential mass murderers?

Everything that I have read says that profiling is not worthwhile because the number of possible future perpetrators is in the millions. Let’s do a quick calculation.

We are looking at young mentally disturbed WASP males from conservative rural towns. WASPs are now a minority. Let’s be generous and put the figure at ½. Males would also be ½. The age range would be about ⅓. Let’s say that 1/5 of the country lives in conservative rural towns and that 1/5 are mentally disturbed.

Putting this together gives ½×½×⅓×1/5×1/5 = 1 out of 300, or about ⅓%. Out of a population of 300 million that gives only one million, not millions. Seems worth looking into to me.