That's just how business works. Profit margins are relatively low on petroleum-based products due to them being heavily regulated. So they'll try to get creative and sell products with their own flavor to raise its value.
It's not particularly bad practice. If it were, all the Apple execs would be in prison. A $999 smartphone? Madness! But people still want it.
Old news but this will give you perspective how much Apple is raking in compared to a few big oil companies:
Apple, The Oil Company? – 5ish Words