Not everyone has an access to this so in a way it's not really a mistake on the newbie trader side, some people just started trading and they just gained their own experience through continuous losses and gains and even if they try and find a school that does this exact thing, they're going to get nothing out of that because the market is volatile and they might not even use a lot of the stuff that they've learned in that school when the actual trading happens, mentors are expensive especially if you don't have a connection.
You're right actually but the issue is how long should they continue on trial and error? I think you're still on the same page with the Op because this itself is one among the reasons why people fail in trading. As a beginner who relies on trial and error to succeed, there's high chance you'll get discouraged in the long run if the lose get too much, that's literally a trading failure. Another reason that can not be overlooked is how majority perceived trading as avenue to bypass poverty which eventually end in disappointment. Getting an experienced mentor is hard and expensive but it is not ideal to bank on self learning through continous loss. It's either you have no intention to trade for long or you want to liquidate yourself.
At first we all might try, but you are right we have to have limits in doing that, don't let what we do not bring anything to ourselves. Just imagine if we only try for a long time, while we don't get any lessons.
Well after we know about something, for example trading. At first we can try first, but we also have to find out more about trading. And if possible, there are people we know who have already entered the world of trading, we can ask them if they don't mind, we can discuss with them, because I am also sure that usually people who have been involved can be more open to discussion.