There are many people who think they can make a quick and easy arcade site in minutes and turn out making several hundred or even thousand dollars a month. However, this is simply not the case the fact is that the market is over saturated. This means that there are too many websites that are being churned out and there is not enough originality within these websites. Some manage to bring in large amounts of traffic like Miniclip and Kongregate. However, these are two of the largest websites in the industry and both have been around for several years.
You will not be able to create the next Kongregate overnight no matter what advertisement or website tries to tell you it is not going to happen. There is simply an over abundance of these websites and while you might be able to craft yourself a nice website that is churning a profit the idea of reaching the levels of Kongregate and Miniclip is simply out of reach for most people.
Furthermore, there are not enough games to go around these websites have hundreds of thousands of games that are available and you have several hundred or thousand that you have access to. If you try to compete as a portal you are going to run into the issue of not enough content or not enough value for your users. This is what is doomed to happen unless you try to stand out as something different from the overabundance of arcade websites. There are some ways that you can improve but for the most case you are going to have to add something unique whether it is a service or some exclusive games.
The main thing is to remember this is not a great way to generate a lot of revenue. However, in time if you put effort into the website you will start to generate revenue.