Gambling can never become an investment. Only way is when you invest in a gambling website. So whatever the profit the owner makes, you can get a part of it. But of you meant by doing gambling, gambling and investment are not even close.
Gambling can be an investment, if you know about what are the casino's do with those people that wants to invest into their site. They are allowing people to invest to their bankroll so that it can make the amount of winning higher for the gamblers. If you want to see an example of it, you can just click my signature and visit it.
You can also invest in their bankroll and it will be a investment in gambling
