Experience will help traders to know importance of their trading capital and its protection. If they can defend their trading capital and more important initial trading capital, they are good traders. Traders can not say they are experienced because they have many years in the market, but practically they can not defend their trading capital. Experience with those traders means nothing and can not help them to even defend their capital, and can not help them to get more profit.
When you are in a market for longer time, you have more experience but if you can not learn from your experience to become a better trader, your experience is useless practically for you and your money. You will also have to consider of quitting your trading career because a bad trader will get more losses with time.
This is so important, having a bankroll management system will protect you for the long term and many things are not doing it properly and they should be looking at this very much so. Lots of traders that spent some time and gained experience will also know that they are not doing every trade they think could be good, the "rushing" to trade is a newbie mistake, usually veterans take their time, sometimes I see them not trade for days if they do not believe in any good trades.
So these two are the most important parts that you learn, obviously another big deal is emotions, because experienced traders do not get their emotions involved with trading and get good results thanks to that as well. If you do all of these, you are going to be better.