I would think elves would also have the mentality that sometimes a regular little is greater than a one-time lot.
I think one of the things that harms Elf RP is that few folks stick with (or survive being in) the role long enough to get a real appreciation of what it could take to be an elf that has to exist within the city. The whole cultural stealing thing is a big part of that, but, I believe, largely because we all view stealing from the human angle. From one of my character reports about two years ago:
Got me to thinking about the odd nature of Elves and stealing. In my mind there is always a hint of anger or mean-spiritedness to stealing. You don't just take something, you take something to hurt the person you're taking it from. I don't think it's always that way with Elves. Elves take things to demonstrate that you can. This is where this whole thing was supposed to be going. I'm not sure it ended up turning out that way. Maybe I'm over-analyzing.
On top of this there's the analogy of the master sculptor. The very best sculptors aren't 24/7 ignoring friends, food, exercise, and other hobbies. That said, if they passed by a piece of sculpture, they might be tempted to tweak it, just that little touch when they're inspired. Like a concert pianist who passes the airport piano. Or the rock star that joins in a street performance, because they were inspired in the moment. That's the elven mindset to me. If there's opportunity + inspiration, they're going to take advantage.
The other part of this is to broaden the scope of "stealing" beyond just the monetary value of what is taken. If the Elf is trying to prove they can get into somewhere impossible to get into, as long as what they take is identifiable, why take the priceless gem? Take one of two favorite earrings instead. You've proven you could take whatever you want. Then plant it back on them, to show them they're just as vulnerable.
It's not the having that is prideful, it's the getting. So, there's a lot to it that requires a nuanced approach to thievery that is so much beyond. I took your stuff and sold it to the pawn shop. Any thief can do that. And they'll have a very short life once they steal the wrong thing - elf or not.