No, you do not get to print money. The value of Bitcoin, for example, is what people are willing to trade it for. You cannot stealthily sustain a 51% attack and

No, you do not get to print money. The value of Bitcoin, for example, is what people are willing to trade it for. You cannot stealthily sustain a 51% attack and will therefore be devaluing your equipment (you are the most invested person in the network likely by far). There are cases where this isn't true. If you are able to rent the hashpower then you can 51% attack without worrying about equipment devaluation; if there is an equally valuable coin which uses the same hash function you could migrate to it after. These are somewhat unlikely; Why would one ever rent out 51% hash? Gaining 51% hashpower is extremely expensive and relies on the network community not reacting to it. But lets say the unlikely happened. If I hold Bitcoin and I understand that someone holds 51% hashpower by credible reports of malicious re-orgs, I simply do not send. At this point I would wrap my tokens onto another blockchain if I needed to send them and wait for a solution. Its certainly not catastrophic, and the majority of people on the network will not lose their coins. The community reaction greatly hinders profitability of an attack. Its also very unlikely - not a significant concern, but also not an unsolvable problem should it become one. Hope that clears things up for you.