In online gambling which you may call it "Virtual Gambling" , you are all alone siting in front of your system. If you are happy winning or sad/crying losing, no one will know it.
There are other ways for people to know it though I don't have friends that are gambling online but still I see others posting their picks on popular places like certain forums.
Sometimes I feel for them having a winning or losing moment when their teams choke in the final stretch.
Disadvantages
1. Less communication - When you play online, you cannot communicate and socialize with anyone because there is no interactions happen.
There are some online casinos that support online chat so we can have an interaction with other players while we are playing. This was no longer a disadvantage because it is already possible today. In fact some Casinos can be contact thru chat if you encounter such problems with the website and they will address your problem easily.
Despite most online gambling sites having a chat on the side, the interactions can be different having a bad chat would feel like you're gambling alone and a good chat could give you a better experience since you get to read their reactions.