Most mistakes in gambling happens because gamblers gambles so many times in a week, they get attached to gambling like it's daily job, what OP said about making mistakes when you stay away from gambling is wrong, you make less mistakes when you are not too attached to gambling.
The casinos even want gamblers to get so attached to gambling, this is one sure way they gamblers will keep coming back, and they will make more money this way.
If you are a smart gambler you must not get used to gambling, have fun gambling but don't expect money flow from gambling, you are just sitting on a time bomb, when the time is up you will likely lose everything or get addicted.
I understand your perspective and agree on some aspects. Gambling becomes a daily habit for many, which is dangerous. The idea that quitting gambling will make you make more mistakes is false. Simply put, less attachment means less risk. Casinos thrive on this bond. Model of business? Keep coming back. Its psychology and opportunism, not rocket science. They play gamblers, not the table. Smart gambling - what an oxymoron. To accept this idea, we must gamble for enjoyment without expecting reward. Expecting to succeed is like waiting for a bus at a train station. Fun, not money, is the goal.
Both players and gambling providers are having benefit of the activity. Did someone force us to gamble? Nope, just our initiative on why we are still engaging in this activity despite of the risk and awareness that losing will always be part of the game. They are just with the business perspective of accommodating the demand from the gamblers and that's just how business works. They are not playing gamblers, and instead, gamblers are the ones who 'play' with their fortune. It is normal to expect for rewards in gambling, what's not is to expect unrealistic amount from gambling such as ideologies of becoming rich in an instant. I'm also a believer that gambling should just be enjoyed to kill time but we just cannot stop the drive to do so since that's how gambling is perceived by many people ever since. Just at least manage the temptation of going or crossing the line of the amount you can afford to engage in this industry.