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.
The only future problem that I see on bitcoin is the increasing price of the transaction fee while the transaction speed become slower over time. This is very bad for BTC in the future because there are a lot of competitors coin that offers cheaper feel and almost instant transaction speed. The only reason why BTC still on is because it is the first mover on crypto market. But when mass adoption happened in the future. Im sure that the crypto that offers the most efficient feature will be the people's choice.