satoshi has a million BTC. He can spend it in 500 BTC increments once a day for half a decade (about 14 million-dollar outlay per day at the current exchange rate). It's true that that BTC won't automatically refresh... Unless, of course, he's spending it on mining equipment and is dominating generation. If he owned enough computing power to generate about half the hashes, then at the current generation rate he would almost be replacing his 500 BTC a day. Later, his ability to generate new currency dies out in the mid-2100s, but of course, if he's controlling the majority of the infrastructure he can just change the rules at that point.
BTC as currently constructed doesn't have theoretically infinite coins, but in practice, the only functional difference between it and fiat currency is the power rests in the hands of a digital oligarchy instead of a government monopoly. The fundamental principle that money is power applies to both scenarios.
If Satoshi spent it on mining equipment, they would have to pay for electricity. And the profits of mining are never again going to be above 6.25 Bitcoins every 10 minutes (and that's assuming ownership of 100% of all ASIC miners in existence); it wouldn't make any financial sense for Satoshi to spend all their Bitcoins on ASIC miners because they'd end up increasing the mining difficulty and drive up their own operational costs. Controlling more than 50% of miners doesn't make any financial sense.
And no, it's not possible to change the rules at any point because there is a large network of exchanges and hundreds of thousands of machines running software which are integrated with and depend on Bitcoin's code not changing. If a small group tried to change Bitcoin's code on their nodes without more than 50% community consensus (and giving them time to update all the hundreds of thousands of machines running the old software), they would fork from the main network and their tokens on that fork would be worthless.
... but if, say, someone with a million BTC spent it on mining rigs and gathered enough power to control 50% of the network, they could institute changes overnight and their rigs' interpretation of the rules would dominate the network. There's nothing in the design of BTC to stop that scenario other than "It costs a lot of resources to pull off," but that means control of the currency is by a de facto oligarchy (of enough rig-owning power to call the shots technologically).
satoshi has a million BTC. He can spend it in 500 BTC increments once a day for half a decade (about 14 million-dollar outlay per day at the current exchange rate). It's true that that BTC won't automatically refresh... Unless, of course, he's spending it on mining equipment and is dominating generation. If he owned enough computing power to generate about half the hashes, then at the current generation rate he would almost be replacing his 500 BTC a day. Later, his ability to generate new currency dies out in the mid-2100s, but of course, if he's controlling the majority of the infrastructure he can just change the rules at that point.
BTC as currently constructed doesn't have theoretically infinite coins, but in practice, the only functional difference between it and fiat currency is the power rests in the hands of a digital oligarchy instead of a government monopoly. The fundamental principle that money is power applies to both scenarios.