In gambling you can invest only in fixed matches, that you have to buy, otherwise you can't be sure you're gonna win 
That's pretty much the same as investing in something with Bitcoin. How can anyone be that sure if they are 100% going to win money from what they put money in? In the end it's all just a gamble because even if the games were rigged there is a small chance of the gambler losing his money realistically speaking of course.Do you have any examples on why you claim that gambling and investing is different from each other?
Maybe what he is trying to say that there is a bigger risk in gambling than in investing. Because in gambling, there is only 40:60 chance that you are going to win, while in Investing there is a bigger chance for you to earn money, let's say for about 70 percent, because the only thing that you have to worry about in this thing is when the site where you have invested your bitcoin is going to run off, something like that.