obviously online casinos can't be profitable in the long run, unless you win jackpot and quit for life. the only gambling activities (that I know of) that can be profitable is poker, sportsbetting and trading (let's agree that it has the same nature as the first two), but you have to invest a lot of time in it, possibly dedicate your life to it, and even then it, most likely, will not be worth it.
If youre talking about jack pots then.. most should just quit placing normal or playing normal casino games.
and just shoot for the mega millions placing $1 ticket instead and hope for god it hits you.