The benefits of dating someone younger than yourself depend greatly, very greatly, on your current age. If you are elderly, the benefits are that your date may look after your needs. If you are a teenager, there is the likelihood that your ideas and wishes will hold sway. This may not be good for your own development! Lets say you are adult, around age twenty.
If you date someone younger than you they are likely to impress you and others with their looks, if not their intelligence. The benefits of being the older one of a pair is that you are more likely to be dominant and take the lead. The danger is that in time the younger partner may tire of this, and of your aging looks, and want a change for the better. However, highly successful men, however unattractive in appearance, have always been able to capture younger, lovely women as partners. Whether those partners found true happiness is another matter...
There are benefits and drawbacks to dating someone younger than you. If you are going to date someone a lot younger than you, then there might be more drawbacks because these people have fewer things in common usually.
The benefits of dating someone younger than you might be that they have more energy. They may do more fun things and keep you on your toes. You may start to feel younger and more energetic just by being around them.
They also are usually better looking because they have not had time to age like you have. Plus, they are more up-to-date on current technology or other events that are known by younger people. Unfortunately, they are usually poorer than you are.