I like what Kasabus said: when you are mentally, emotionally, and financially ready, you can start trading. Knowledge and experience will be created during your trading.
most beginners even try trading first instead of learning and understanding how trading is done in the market. but what you said is right, those who have studied with a lot of knowledge should also try to gain enough experience. some exchanges provide a demo account. it can be done for those who are not strong enough financially. but it's pretty good for trying to apply learned skills. but to get a more convincing sensation, trading with small capital can be done. trading will not always be profitable, and we will also sometimes lose.
We've all became beginners in trading and we can say our adapted knowledge from different resources through our research will not be applicable unless we try applying it in actual trading. Yes, experience is necessary for is to learn more. Not all strategies and market analysis could be learned through self-study but they could be acquired from our trading experiences.
Trading could be for everyone but we have to keep in mind that not everyone could get rich or be successful in trading because not everyone could handle its risks.