But you also need a large amount of btc's to be invested as no player will play in a gambling site if the site has less bankroll.
You also need a team here includes coders, developers, support team etc. which are also part of your financial expenses regularly together with promoting, advertising, hostname etc.
There's a hidden expenses to so watch out.
Yes maintaining a gambling site is not that much easier and cheaper. Once he got everything set up and running live, you need to start a new thing, called advertising of your new gambling site. Many people are doing this by signature campaign which would cost them around 2 bitcoins every week.
But I believe starting and running a gambling site would be a better way to grow our bitcoin with respect to this current trend. Many people are regularly doing gambling just for fun as part of their lifestyle. So gambling house would be the better way for making more bitcoin from our bitcoin investments.