What happens when there is so much halving that the reward for mining bitcoin is extremely low and the cost of verifying the blockchain for the miners exceeds the reward of their bitcoin?
I do not think this is possible. Reasons:
1. Bitcoin is a deflationary currency, decreasing supply but increasing demand.
2. If bitcoin mining and transaction fee is not favouring today, it will favour tomorrow because bitcoin price is volatile. This encourages miners.
Absolutely it is! A lot of people said that bitcoin is just like gold, but in a digital or virtual form, which is true based on its features.
Bitcoin is not predictable, so there's a lot of possibilities that it might happen. If we overthink too much negatively, that's what will make people think that bitcoin is not efficient in the long run, not reliable in the future. Bitcoin is unpredictable, as its price goes up and down, you are the one who are accountable on making it profitable depending on the situation.
But I know that some people are surrendering their devices to mine bitcoin due to high expenses that's why they invested to it instead of mining it.