The biggest benefit of Sim racing is the fact that you cannot get hurt if you crash your car in the game, no matter how bad it gets. This, along with the fact that most games let you restart after you crash or whenever you race, is why some racing drivers in real life are not that good at sim racing. They cannot pace themselves and will try to go above the limit, crash, and lose in front of people with more caution and zero track experience.
In professional simulators that are made for top-tier events, you will feel similar things as you would in a real vehicle when the car slides or even other scenarios. When a budget sim rig is concerned, there will be no such thing, and the force-feedback gaming wheel will not come close to many real-life experiences.
Despite this, there are things that can be learned from sim racing. The biggest and most important thing is that you can learn a track from real life by driving on it in a simulation game. If you drive enough laps on a virtual track, you will eventually memorize it. It depends on the track, the game that you are using, and your objective, but it can be done.
Ideally, you will find something that shares your vehicle's configuration, like an RWD vehicle if you have one or an FWD one if that is what you are going to bring to the track. Otherwise, your experience will not add up properly in real life, or vice versa. Refrain from getting the most powerful car in the game; you will not learn as much as you could from an inertia mobile.
Within a week of practicing for one hour each day, you should now know the track by heart. It helps if you do time-attack events in the game that has your track of choice and you are alone on the track. After several days of learning, add a few opponents to see how it will be in real life when you find others on the track. Hint: it is not as easy as in a game in real life, but having a bit of virtual experience beats zero experience.
Second, as the folks at Team O'Neill note, using a simulator – even a cheap one is a great way to experiment with various vehicle settings without spending a dime. Ever wonder what changing your camber will do? But what about brake balance? Or stiffer springs or softer shocks?
Third, if you use a sim racing game, there is a good chance that you will begin to learn the racing line on a track. Once you get good at it, it will help you spot it, even on a track that is new to you. It comes in the form of experience, and it cannot be bought.
On the other hand, you cannot simulate the G forces in a budget sim rig, and the same applies to things like temperature and smell. In the case of the latter two, you will never know if your virtual racing car is encountering an issue just by scent, and nothing can prepare you for the heat that will be generated by your racing car.
You can, however, prepare your mind to have your eyes looking at the right spot while driving. It is nothing like the real thing, but you must train yourself to look where you want to go, and this is an essential skill that few people talk about when driving a car. Its applicability in real life is more than for performance. It also is a safety thing, as looking away from obstacles will help you avoid them.
Good habits, such as sticking to the racing line, having smooth inputs, and being calculated, will work in real life, possibly with even better results. Practice as much as you can, focus on doing things right—and the results should follow.