Isn't about a user cracking the code, to apply a change on the network then more than 50% of the nodes should run with that change. In theory, this could be possible, but more than 50% of the people should be agreed with this idea and that's the complex part.
When governments print more money the coins lose their value, that could happen to bitcoin if a fork like that comes.
So, my answer is, yes, it can be manipulated but it will never happen.
I thought for such substantial changes you need more than fifty percent. You don't fly need most of the miners but also all exchanges to upgrade the wallets. I on't know precisely how it works but I remember Andreas Antonopoulos said that in order for the supply to be changed you need more than just a lion share of the hash power.