There are some differences: investment platforms wont kick you out if you manage to earn money. Gambling sites do that. If you are loosing a lot, gaming sites make your limits go up. If you are winning a lot, your limits go down. Investment sites dont do that.

They also assign "consigliere" to you if you loose a lot. He is supposed to create a personal relationship with you. If you try to stop playing, that person will try to get you back into gaming.

You are not betting against investment platform itself, you are betring against other people on it. That is major difference.