The Saudi's are taking a harsh revenge on their enemies particularly Russia and Iran.

Saudi Arabia which is Sunni has had a long term fued with Iran ( Shia ) going back more than a thousand years.

The Saudis know that they can sell oil cheaper than Iran and Russia and that can easily cause financial instability in the other countries by selling their oil cheaper than the others can produce it for.

The whole situation is based on political strategy, using their economic power to disturb their enemies.

When they feel they have made their point, then OPEC will reduce oil production and higher prices will be restored.