I'm not sure if the person is allowed to use country services like healthcare, but I assume that also factors into the high-income requirement.
This is an anecdote, but I remember meals easily being 20-30 USD for basics. A cup of soup (tiny) was 13-14 USD and it wasn't in a tourist area. I'm sure someone will reply with cheap food found somewhere in iceland but as someone from the US, the cost of food in proportion to the amount and quality, it was surprising.
I hope someone chimes in with the rent cost. I'm not sure where that sits.