With all the wildfires ravaging Europe right now, I often see that some of them are presumed to be caused intentionally. Why would someone even do that or does that mean something else?

Please someone explain this to me as I am completely lost as to why someone would "Intentionally" cause a wildfire.

PS: Currently one of the huge wildfires in Spain is at a 30 minute drive from my house and a 15 minute drive from my office.