The point is:
You are 'guaranteed' to make more coins with investing in a coin...than actually gambling with that same amount.
Who provides/offers this guarantee? If investing in a coin is guaranteed then all people will invest all their money on it, there is no guarantees at all. There is always a risk of losing money when you invest your money in a coin.
Why not 'bet' on any cryptocurrency of your choice?
- A new promising ICO.
- Or a coin you like.
- Or think is technically good.
- Or is hyped.
- Has a great name/logo/website.
Above things cant guarantee you will make profit.
PS: Aslo ignore this if you are a whale and can afford both, anyways

Who can afford both things are not always whales, I'm not a whale but I always use my money that I can afford to lose in both investing and gambling. It is just about preferences, we should not force ourselves if we do not know what is the risk on both activity.