I'll meet you halfway, and say it's more like you owned all the raw plastics and metals, and the bank payed for a team to fabricate those raw materials into a car for you, and then you tell the bank thanks for the car, now **** off.
...That's playing dirty IMO.
It's not even remotely comparable to what happened though.
If you want a simplistic analogy, it would be like if you were 5 years old and your dad agreed a deal with his friend where, in exchange for paying for your schooling, 70% of all the money you earned in your lifetime would go directly to his friend.
You probably wouldn't be overly keen on a deal such as that.
The previous, undemocratic regime signed a long-term deal with mainly the Anglo-Persian Oil Company (later BP), on very bad terms and which enabled APOC to make enormous profits.
The British government was making far more from Iran's oil than Iran was. Moreover, the supply of oil was key to transforming the Royal Navy from coal to oil based power, helping win WW1 and maintain British Imperial power.
They had certainly had their money's worth out of the deal they signed.
When a new regime took over they didn't really like the terms of the deal, a bit like how Britain's American colonies didn't much like 'taxation without representation'.
And just like the colonials, when their attempts to get a better deal where thwarted, they took more radical action.