Stealing is perfectly fine as long as it is done big banks and big corporations.

Both. Huge businessmen and corrupt officials steal for their personal gratifications which is driven by their own greed. On the other hand, poor people tend to steal in order to survive. Scarcity of basic necessities is the usual reason behind this, it pushes them into their limits to commit stealing even though they knew from the very beginning that it was not a good thing. They are like facing a "no choice" situation so I can't blame them.
If you will ask me if they're the same, I say YES. It doesn't matter whether you only stole a piece of apple or millions of money, stealing is stealing it was a sin. However, I believe that sometimes in life the end justifies the means so I'll be more compassionate for the poor ones if proven guilty

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There is a big difference here, and most rich people get where they are by stealing profit from their employees. Profit is really just unpaid value that workers created so they are taking back what was taken from them.