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?