外汇市场是全球最大且最流动的金融市场之一，每天交易量达到数万亿美元。在进行外汇交易时，投资者经常会遇到手续费的问题。为了理解为什么外汇会扣除手续费，我们需要了解以下几点原因。

首先，外汇交易是通过外汇经纪商进行的。这些经纪商提供交易平台和流动性，使得投资者可以在其中进行买卖操作。作为提供服务的机构，经纪商需要从中获取利润。手续费就是其中一种收益来源。

Secondly, the foreign exchange market involves various intermediaries, such as banks and financial institutions. These intermediaries facilitate the transfer of funds between different currencies and provide liquidity to the market. They incur costs in managing these transactions and also need to generate profits to sustain their operations. Therefore, they charge fees to cover their expenses and earn a profit.

其次，外汇交易的执行涉及到成本和风险。在买入或卖出某种货币时，经纪商通常会为投资者提供报价，并在交易后立即成交。然而，在外汇市场上存在着市场风险和流动性风险。为了抵御这些风险，经纪商会留出一定的利润空间，以确保自身的稳定性。手续费的一部分可能即是为了覆盖这些风险。

Thirdly, the forex market operates 24 hours a day, 5 days a week. This means that brokers need to provide continuous support and services to their clients, including customer service, technical analysis, and trade execution. These services require human resources, technological infrastructure, and maintenance costs, all of which are funded through various means, including charging fees.

此外，外汇市场的监管与合规要求也需要经纪商承担一定的费用。各国的金融监管机构通常对外汇经纪商进行监管，并要求其遵守一系列合规规定。为了满足这些要求，经纪商需要支付注册费用、交易许可费用以及其他相关费用。将这些成本转嫁给投资者是经纪商的一种常见做法。

Finally, it's important to note that forex brokers offer different types of accounts and trading platforms, each with its own fee structure. Some brokers may charge a fixed fee per trade, while others may have a variable fee based on the size or volume of the trade. It's crucial for investors to carefully compare and consider these fee structures before choosing a broker.

In conclusion, there are multiple reasons why forex trading incurs fees. These include the need for brokers and intermediaries to generate profits, cover costs and risks, comply with regulatory requirements, and provide ongoing support and services. Investors should be aware of these fees and consider them as part of their overall trading costs when engaging in foreign exchange transactions.

总之，外汇交易收取手续费是因为经纪商和中介机构需要盈利、覆盖成本和风险、遵守监管要求，并为客户提供持续的支持和服务。投资者在进行外汇交易时应该注意这些费用，并将其作为整体交易成本的一部分加以考虑。

英文翻译对照：

Foreign exchange market is one of the largest and most liquid financial markets globally, with daily trading volume reaching trillions of dollars. When engaging in forex trading, investors often encounter the issue of fees. To understand why forex incurs fees, we need to consider the following reasons.

First, forex trading is conducted through forex brokers. These brokers provide trading platforms and liquidity for investors to buy and sell currencies. As service providers, brokers need to generate profits. Fees are one source of revenue for them.

Second, the foreign exchange market involves various intermediaries, such as banks and financial institutions. These intermediaries facilitate the transfer of funds between different currencies and provide liquidity to the market. They incur costs in managing these transactions and need to generate profits to sustain their operations. Therefore, they charge fees to cover their expenses and earn profit.

Third, executing forex trades involves costs and risks. When buying or selling a currency, brokers typically provide quotes to investors and execute the trades immediately. However, there are market risks and liquidity risks in the forex market. To mitigate these risks, brokers allocate a certain profit margin to ensure their stability. Part of the fees may be used to cover these risks.

Additionally, the forex market's regulatory and compliance requirements also impose costs on brokers. Financial regulatory authorities in various countries generally oversee forex brokers and require them to comply with a set of regulations. To meet these requirements, brokers need to pay registration fees, licensing fees, and other related costs. Passing these costs on to investors is a common practice among brokers.

Moreover, it's worth noting that different types of accounts and trading platforms offered by forex brokers have different fee structures. Some brokers may charge a fixed fee per trade, while others may have a variable fee based on the trade's size or volume. Investors should carefully compare and consider these fee structures before selecting a broker.

In conclusion, forex trading incurs fees due to brokers and intermediaries needing to generate profits, cover costs and risks, comply with regulatory requirements, and provide ongoing support and services to clients. Investors should be aware of these fees and consider them as part of their overall trading costs when engaging in foreign exchange transactions.