Set the Instant Pot to Sauté mode and add the olive oil.
Add ground beef and cook until browned, breaking it into small crumbles.
Drain any excess grease from the pot.
Stir in salt, pepper, garlic powder, onion powder, and dried oregano.
Add 0.5 cup of the water and use a wooden spoon to deglaze the bottom of the pot, scraping up all browned bits.
Turn off Sauté mode.
Layer the broken spaghetti noodles over the beef in a crisscross pattern to prevent clumping.
Pour the marinara sauce and the remaining 2.5 cups of water over the noodles without stirring.
Secure the lid and set the valve to the Sealing position.
Select Manual/High Pressure and set the timer for 8 minutes.
Perform a Quick Release of the pressure once the cook cycle is complete.
Carefully open the lid and stir the contents thoroughly to combine.
Allow the spaghetti to rest for 5 minutes to thicken the sauce before serving.