This has been said elsewhere, but for your benefit, you can't steal anything with a 51% attack, it just allows you to defraud others by double-spending coins you already control (and do other less-directly-profitable things like "unconfirming" transactions when the blockchain reorganizes).
Of course, you could also just nuke the entire network by not confirming any transactions. But you can't steal from people directly.
when states issue more currency to buy bonds, do you call that stealing?
This clearly inflation and possibly fraud (depending on what claims were made when you bought the crypto coin), but I don't think you can call it theft (unless you think all inflation is theft).
> when states issue more currency to buy bonds, do you call that stealing?
Nope, definitely not stealing without question. It's economic policy which is a lot more nuanced. Not saying it's never stealing, but issuing more currency has been happening for decades and it's no surprise to anyone.
---
Your example and double spending are definitely not the same: with double spending you are basically giving coins to an exchange, which you later "steal" back via forking the chain. This is against everyone's expectations AND against the ToS of all exchanges (which you break if you double spend deposited coins).
Issuing more FIAT currency is very similar to mining (pumping more money into the economy) which I don't think anyone considers stealing. Double spending however..
Of course, you could also just nuke the entire network by not confirming any transactions. But you can't steal from people directly.