The time has to come from somewhere

Sustained practice is taken out of a life, not added to one.

The hours required for the long middle are not spare hours, because almost nobody has spare hours. They are taken from sleep, from evenings, from friendships, from other interests, from the flexibility a household relies on, or from paid work. That is the actual transaction, and it is usually paid partly by other people. Anyone deep into a demanding skill has a set of things they no longer do and, often, a person who covered for them while they were in the workshop. It is more honest to say so than to describe the process as a matter of discipline.

This is also where circumstance decides a great deal. A person with predictable hours, a room to work in, tools already bought and someone nearby who is better than them is in a different position from a person with none of those, and the difference is not effort. Some skills demand access to expensive equipment, a particular city, or an early start that only certain childhoods provide. Saying this does not mean the outcome is fixed. It means the same result costs wildly different amounts depending on where a person begins.

The reasonable response is neither to pretend the cost away nor to treat it as disqualifying. It is to look at the specific trade in front of you and decide whether you want it, knowing what it takes from elsewhere. Plenty of people look at that trade clearly and decline it, and they are not making a mistake. The people who regret it are usually the ones who never looked at it directly and drifted into paying the cost without deciding to.