Unfortunately the best (only?) true way is by doing. I suppose prospecting is the best analogy I found. You study geology and gain some theoretical foundations so you understand the relationships and can analyze the results, but you have to go out in the terrain and get your hands dirty so to speak to get true intuition and understanding.

Also, doing it on your own is tricky. You have to constantly talk and mingle with others or you quickly lose insight into current developments. Having a group of people to bounce ideas off of is incredibly important. On your own, every single small topic is a potential rabbit hole that you can spend endless time researching. In a crowd, someone has already explored that rabbit hole most likely and can give you practical pointers. At risk of sounding like a marketing prospectus, there's real synergy in being part of a team. I dare say the age of lone wolf traders is gone. They've been arbitraged away. Successful people have teams behind them.

So I'd say the best way to gain market knowledge is to join a systematic trading shop (in almost any technical capacity) and once inside, you just talk with the others. People in systematic firms tend to have a solid academic approach and are usually more than happy to teach and enlighten anyone interested.