It is the duty of a Muslim to learn fiqh as part of learning Islam. While some things are clear and it is easy to discern wrong from right and evil from good, there are things that are less clear-cut and Muslims follow the guidance of God, through the Qur'an and the teachings of the Prophet, the Sunnah, for clear instruction. The clarity that the teachings of Islam brings is one of the things that makes it superior to other religions whose followers have no solid foundation in the rules of the religion nor guidance in life. When a Muslim has a question about their religion there is usually a good answer/solution found in the Qur'an or hadith books, but things can become quite complicated based on different situations.
The Prophet Muhammed (SAW) said: "That which is lawful is clear and that which is unlawful is clear, and between the two of them are doubtful matters about which many people do not know. Thus he who avoids doubtful matters clears himself in regard to his religion and his honor, but he who falls into doubtful matters [eventually] falls into that which is unlawful, like the shepherd who pastures around a sanctuary, all but grazing therein. Truly every king has a sanctuary, and truly Allah's sanctuary is His prohibitions. Truly in the body there is a piece of flesh, which, if it be whole, all the body is whole, and which, if it is diseased, all of [the body] is diseased. Truly, it is the heart." [Sahih Bukhari/Muslim]
A wise person once said: "Life is as difficult as you make it". And when it comes to living your life as a good Muslim these words ring true. I sometimes get asked for advice or am given questions that are in fact particularly complicated and sometimes I just have to answer, "Sorry, I don't know. I recommend you consult a learned scholar". Things can get very complicated very quickly because people have committed sins or broken the law and this has led to further sins and harming of people other than themselves and they have to find a way to solve many problems. It always leaves me wondering beyond the initial "why did you commit that first sin in the first place?" - "WHY did you not stop and repent but instead go on to cause yourself and other people more trouble? I've noticed that often, big sins start off small with a 'little' lie and then things start to snow-ball, more lies are told, then big sins are committed and people get hurt. Had a person not allowed the problem to grow or not lied in the first place they would be much better off.
An intelligent person learns from their own mistakes and avoids them. A wise person also learns from other people's mistakes - she or he observes them and recognizes their errors and does not repeat the same mistake. A wise and intelligent person also recognizes the importance of knowledge and spends time reading up on fiqh and informing themselves on the complicated issues and sins they should avoid altogether.
In my opinion, one of the most beautiful things in Islam is that seemingly innocuous or ineffectual rules are some of the most powerful and beneficial to people. These are the rules of avoidance, order and discipline. Non-Muslims may point to them and laugh or wonder in amazement at why Muslims are asked to avoid certain things and why it is so strict, but it is not until you realize that everything is connected and the consequences are more complex and far-reaching than they first appear and that there is a bigger picture, only then do you realize the hikmah, or wisdom, of those rules.
One of the most well known rules in Islam is that drinking Alcohol is forbidden, and the grand majority of Muslims know this and actively avoid drinking alcohol. This rule is well known and well documented and you don't have to be Muslim to recognize that Alcohol is a scourge on society (whether you agree or not is not the point). But what is not well known and might appear innocuous with regards to alcohol is that Muslims not only are forbidden to consume it, but are forbidden to trade in it (either buying or selling), or to serve or be served it, or to frequent a place of drinking or sit at a table where people are drinking, or to be part of a drinking crowd.
There are two types of laws that govern such rules - well known specific rules mentioned in the Qur'an and Hadith, such as clear statements from the Prophet saying that drinking alcohol is forbidden, and unspecific or indirect laws � laws that apply in general situations, such as not putting yourself in view of other people in a way that might make them think you are committing a sin and/or inspire them to commit those sins themselves. While such a law does not deal specifically with alcohol it is still relevant and applies to such situations as mentioned above.
One of the main reasons people sin is because it is made easy to do so and they see other people doing it. People need to be aware that something is a sin as well as have a good deal of will power and faith in oneself and in God to avoid sin when it is presented to a them in an alluring and attractive manner and their friends coax them into it. Only when they fall into this trap and get deep into sin do they realize their mistake and see the consequences and they understand the hikmah behind these rules.
A wise Muslim knows that they not only need to avoid the sin itself, but also avoid things that may bring themselves or other people closer to committing sins or leave them in a doubtful state. If a Muslim never attends a party, never joins a drinking crowd, does not go to a place of alcohol, then it makes it far more difficult to commit minor sins that would eventually lead them to fall into the trap of committing major sins. A wise Muslim also avoids the company of sinners and instead seeks the company of friends who remind them of God and increase them in knowledge and faith.
Islam is simple and its aim is to make the life of a believer safe and easy. Islam aims to keep the believer safe from evil and teaches avoidance of sins. Islam only becomes hard and complicated to follow when people ignore the safe-guards and break laws and commit sins. The greater jihad is to keep oneself free from sins and Allah shows us that this jihad can be made easy with the understanding of His religion through the study of His laws and guidance and the active avoidance of sins or things that may lead to sin. And even when we do sin, Allah, in His Beneficence, gives us the opportunity to right our wrongs and seek repentance from Him, and He is Oft-forgiving and Most Merciful.