To make sure it’s not long-run possible for the state to exceed 500 GB, storing 500 GB should cost 500,000 ETH per year, so storing 1 byte should cost 0.000001 ETH per year,
Charging for storage naturally disincentivizes storage, but is there an economic/incentive/arbitration relation between 500GB and 500,000 Eth? Or is it just a presupposition that users will value storage on the ETH blockchain at 0.000001 ETH/byte? If I, and everyone else, value storage an order of magnitude more, then what actually stops the state from growing to 5TB? What happens when the state is full? The EVM throws errors on new state saving ops?
Only validators are paid to run full nodes, average user isn’t going to regardless. Validators and businesses that use ethereum can get larger drives.
People use light clients because the state is too big, not because they don’t want to run a full node. They don’t want to run a full node because it is inconvenient. Make running a full node convenient and they will.