Gambling is a different thing entirely from doomscroll because you stake money and the possibility of you losing your money is high. Gambling messes with your emotion and can fustrate you in the long run if you don't gamble with caution and self control.

Doomscrolling is done for fun and you have nothing to lose or any consequences attached to it when it's done excessively. The only disadvantage that I see in doomscroll is that some people get carried away with their phone and neglect people around them.