Living in ketosis is fine if you live a moderately active to sedentary lifestyle. But I’ve read from credible sources that it isn’t suitable for athletes and those who have to occasionally do power exertion or require bursts of energy. Keytones just can’t react as quickly as glucose in the blood.
That’s why distance runners almost always eat a meal of pasta or other starch before an event. It’s short term but effective energy. Ketosis is more on the slow-burn scale.
That's about 99.9% of the population.