Dimitrijević was key part of Serbia’s power structure at the time.
It seems to be the case that the Russian military attaché in Serbia, Viktor Artamonov, financed Dimitrijević plans. Whether St Petersburg knew about this is unclear, but why would Artamonov use his private money to pay for foreign terrorism?
Russian intelligence had been able to read Austro-Hungarian diplomatic ciphers for a while before the war, so it is likely that St. Petersburg was aware of what Vienna’s probable reaction to the assassination would be.
So no, it wasn't just G Princip.
Today organisations like ISIS use dumb and angry youths like G Princip.
Well, that is insult to many freedom fighters and with your logic creating of US is "revolutions of dumb people". For your information (I suggest go read because you obviously didn't) - Austria wanted a war, the assassination was just a good cause for them. The assassination happened in Bosnia (in territory they annexed) but they gave ultimatum to other sovereign state (Serbia) to conclude investigation with their own force on a soil of independent nation - I wonder what would happen if Turkey wanted to send its own investigators to conclude independent investigation of dead Turk in Germany.
For Serbs G.Princip was freedom fighter - Bosnia historically was Serbian land (Raska), most of muslims come from Serbs converted to Islam, and today half of Bosnia is entity called Republic of Srpska - Austria really had no business to be there in first place.
If the Turkish ruler (rather than a random Turkish citizen) was killed in Germany than clearly Turkish authorities would be invited to help with the investigations. There was a relevant recent event when the plane of the Polish president crashed in Russia [1].
[1] https://en.wikipedia.org/wiki/2010_Polish_Air_Force_Tu-154_c...
Yeah, he was a tool of others. But he was the one who pulled the trigger: the spark that ignited in the primer of his pistol cartridge is still burning.
With your logic we could just say "Wars simple happen because of humans - so first humans on Earth are responsible for all wars".
Go educate yourself a bit before just commenting.
The sparks happened before with two Moroccan crises, German naval buildup, etc. It's much more complex than your simple view.