Without a doubt having a mentor is the optimal choice as they can help you to identify the information that is accurate from the one that is false, this will speed up your development to an amazing rate and even help you to create your own strategy, however why this is not more common? Because finding a mentor is really hard, even if you knew someone that knew how to trade the markets there is not guarantee they will want to teach you as they will see you as a potential rival.
There are a lot of trading sources of information online. However, the situation of being in actual trading is different which I think is one reason why even if we look and spend a lot of time doing an online search, many people are still not satisfied enough, and many we're still broke. It could be a reason as well to make important why we should have to create our own rather than following any person (even have a mentor) as to know one day this person will also leave. It is very important that we fully understand trading the way it works in order to succeed, not by relying on others.