Ijaz Ahmad Khan Mayo

Your question seems to indicate that you want to know the disadvantages or bad things of currency (especially Forex/online currency trading). I will explain it in a simple and clear way:
Disadvantages of currency/forex trading
Very high risk
The currency market changes very quickly, a big loss can occur in a few minutes.
High probability of loss
New people often trade without knowledge and money sinks.
Leverage is dangerous
The convenience of making large trades with a small amount of money also increases the loss many times over.
Fraud and scammers
Many fake companies and people online deceive by luring them with “daily profits”.
Psychological pressure
Greed, fear and haste lead to wrong decisions.
Shariah issue (important point)
According to many scholars, general Forex trading is illegal due to interest and uncertainty, especially due to swap/overnight charges.
No steady income
This is not a job or guaranteed work, today's profit may be tomorrow's loss.
Disadvantages of common currency (cash money)
Inflation reduces value
Risk of theft or loss
Just having money does not increase money
If you want, I can also tell you:
✔️ Better ways to earn halal
✔️ Safe investments in currency
✔️ Online jobs that are relatively low risk
Just tell me whether you are asking to learn or to invest?