Traders are human and when they undertake anything new – including trading – they come to the table with certain preconceived notions or habits, which I'll refer to as mindsets. It pays to take advantage of your education and experiences and apply appropriate lessons to any new challenge, including becoming a successful trader/investor.
The problem arises when those mindsets, developed over a lifetime, are in conflict with habits that are required to succeed in the new endeavor. For some it's a relatively short lifetime of experience and for others it quite lengthy. Nevertheless, bad habits are difficult to overcome, and that can make it very difficult to succeed as a trader.
I often write about the importance of good risk management and money management. Someone who has spent years running up credit card debt, living beyond his/her means, or buying things to impress the neighbors obviously lacks the discipline to be careful when managing money. I'm not suggesting a trader must be frugal. But trading discipline is not easy for someone who spends carelessly and does not understand the importance of avoiding debt – especially at high (credit card) interest rates. Being careful with trading dollars and getting your money's worth from the commissions and fees you pay contributes to success. The frivolous spender may have a difficult time with that aspect.
On the other hand, it's possible that the too frugal trader may not be willing to invest money in insurance or in making adjustments. It's certainly not frugal to take excessive risk, but an inclination to watch every penny can get in the way of trading decisions. Maybe this is one reason why so many who advocate a frugal lifestyle also prefer passive investing.
Unless you own a portfolio of very conservative positions, occasionally (more often for aggressive traders) you find yourself in a risky situation. It's far better to make decisions based on common sense, previously made plans, and the ability to think well under pressure. Individuals who are accustomed to being ruled by their emotions are not going to do well under these conditions. Thus, if you have a mindset that allows those important, spur of the moment, decisions to be made when emotions are in control, that's deleterious to your chances of winning the trading game. Those who have their emotions under control, are far better placed to make a good decision under pressure.
Do you have the mindset that allows sloppiness in your daily life? Can you overcome it and become more disciplined when trading?
Do you think of trading as dealing with Monopoly money? Is trading a game to you? Or do you have the mindset of a gambler? That's not the mindset of a serious trader who understands that taking big risk, and losing, can be ruinous.
Do you have an understanding of where your comfort zone lies and the importance of trading within that zone? That's a positive mindset because it makes it easier to know when to take your profits or adjust a position.
My suggestion is simply to be aware of the recommended characteristics of a successful trader (you can find various opinions online) and be certain that you are aware of any habits that are in conflict with those desired traits. Being aware is the first step towards not allowing those habits to interfere with your quest.