You cannot boast of being an expertise when you do not have the appropriate knowledge. However, appropriate knowledge cannot guarantee expertise either.
You need knowledge before you even try to be an expert in anything. You will never become an expert about something that you have no any knowledge about. Even if you have too much knowledge about something, this will not make you an expert in the area. This is why you have to always continue learning. You will have to keep increasing your knowledge in your life to the end.
However, what makes things a lot easier is that you only learn what you want in the niche you have chosen. For instance, if you want to be an expert in baking cakes, you will learn only about this. If everyone knows that your expertise is in cake baking, they will never ask any question about barbecuing to you. But if someone asks about cake baking and you cannot find the right answer to the question then your claim of being an expert is questionable and you come across as a non-expert.
Do not think of using the internet to increase your knowledge; this is because it has only information but not knowledge. If you want to increase your knowledge on any subject then you will have to use both offline and online resources. Remember always that no amount of knowledge is ever enough where expertise is concerned. You will be required to enter into the depth of the subject. You may also think about getting books, and CDs concerning the subject. You may even think about joining a course. This is always a good idea. Even if you consider yourself as an expert about something, attending a fresh course will update you on your knowledge and will show you another important thing – how different experts tackle the subject.
Keep in mind that being an expert does not mean to be closeted or proud about your own knowledge. You need to be open so that you can gain more knowledge and in order to try out new things in your niche. You have to observe how other people go about the things that are of interest to them. You are able to become an expert in something that you have a love for. In case you love something then you will want to check on how other people deal with it.
Even if the internet cannot give you direct knowledge that you need, you will find vast material in the annals that you can get. An example is, when you are able to buy CDs or books that can improve your knowledge. Always be on the lookout for different sources of knowledge and never hesitate to download something that caught your interest even if you have to buy it. Everyone is an expert in one area and no one can take such privilege away. It is up to you to keep enhancing what you have already acquired.