The only true way to profit from 'house' gambling is to be the house. It is already arranged that the house will always profit in the end.
If you gamble against people, like poker, then you need to learn the people and avoid online gaming some. I have seen some real crazy people online and many do not follow a logical approach which makes it hard to work against them
Somehow that is true but only if you have enough balance to let them to win first because to attract people you need people to have a big win or there will no one to play on your site. There will not be that easy to get some profit on gambling though