Arson in my neighborhood

I live in the hot Sacramento Valley of California.  The landscape is dry during the summer with high grasses and oak trees.  I am sure you have seen the dangers of fire during these dry hot months.  With all of the California wildfires on the news.  It can just take a spark from a lawn mower, and a fire starts.  I live in a residential neighborhood, but just a few minutes away is a more rural area.  My best friend lives out there, and has the grass cut around her property for safety. 

When driving out to the grocery store on Sunday, I saw a field that is really close to her home that was blackened by fire.  I talked to her tonight on the phone, and she said that she smelled fire.  Apparently there has been someone in the area starting fires, and they started another tonight.  There has been at least one a day.  They have left a piece of paper with a swastika and the time the fire has started.  The sheriff had been around to question her and her neighbors to see if they had any leads or saw anything suspicious. 

I can't understand why someone would want to put so many families, homes and fire crews in danger.  It is simply beyond me.  A windy day, an accelerant or a variety of factors can cause these fires to go out of control quickly.  I hope they catch the arson soon, before something more tragic than a burned field occurs.  I wonder what kind of cheap thrill is obtained by this?