How can I prove you wrong, you ask?
Well… what if I showed you this:

And then this:

They say a picture is worth a thousand words.
The Orca is a formidable predator when alone and even more so as part of a pod. But even a whole pod of orcas will think twice before they take their chances against the absolute monster that an adult bull Sperm Whale is.
Yes, the 25 foot length (9 meters) and 5 tons that they weigh is huge, but it is dwarfed by the near 80 foot, 40 ton monster. One-on-one, a solitary Orca would do well to stay away even from the juveniles; Sperm Whale calves weigh about a ton coming out of the womb – the weight of a Great White Shark!!! – and very quickly they’ll surpass the Orca’s weight.
One-on-one, not just would the orca get beat, it would get destroyed.
This guy would like a word…

“Stupid killer whale”
At 88,000 pounds (40,000 kilograms) in weight, and 16 meters (52 feet) in length, the sperm whale is over 5 times larger than the killer whale. These guys are also the largest toothed predator living today. It takes an entire pod of orcas to attack even one, and even then, sometimes the hunt isn’t successful. Females are targeted, as they are significantly smaller and less aggressive. However, there are almost no cases on bulls being attacked, most likely due to their sheer size and aggression. If an orca and a sperm whale were to fight, the whale would almost certainly win.
This guy also feels offended:

“Haha, tiny”
There is absolutely no way any living animal could take on a blue whale. The killer whale weighs in at around 12,000 pounds (5,400 kilograms), and measures 8 meters (26 feet), which is pretty huge. However, it is dwarfed by the blue whale, who tips the scales at 440,000 pounds (200,000 kilograms), and measures 30 meters (98 feet). The largest animal to have ever existed, this whale has a significant size advantage over every other creature. The behemoth could use this size advantage in a battle between it and an orca, and it would stand victorious.
I think I’ve proven you wrong.