Currently miners get the block reward and transaction fee for every block they find. However this is only paid to the successful miner. So every ~10 minutes there are plenty of miners who have used electricity but who don't win the cryptographic race to earn some bitcoin.

If they don't win often enough then eventually it becomes unprofitable for them to continue and they will stop mining.

We tend to see miners switch off their machines around the time of a halving (when the reward per block halves every 210,000 blocks - every c4 years) because it takes some time for the network to settle down into profitability. Also if the base electricity cost were to rise (as we'll likely see across the world now) then this could also cause a temporary disruption to mining profitability and therefore some miners going offline.

However in cases like this, not all is lost.

Instead, every 2016 blocks (~2 weeks) the network will adjust the mining difficulty to try to keep to c10 minutes between blocks based on the computational power int he network. This means that the cryptographic puzzle will become easier to solve if the hashrate on the network decreases or harder to solve if it increases. If the former, then this will entice miners back onto the network since they are more likely to find the next block and win the reward.

In the post-block reward world then the expectation is that fees alone will be enough to sustain miners. However if the price of BTC falls then some miners may decide to switch off their machines because it's no longer profitable for them. However this would reduce the hashrate on the network and then in the next difficulty adjustment the puzzle will be easier to solve, therefore making it more profitable for miners to re-join the network because they're more likely to win the block race and it's cheaper to solve the puzzle since it's easier.

So this automatic adjustment of the difficulty is what regulates blocks and helps keep the network profitable for miners.