That's why Bitcoin should not be compared to gambling because of the size of their difference, it is because Bitcoin can be considered a long term investment and gambling is not, but rather a type of entertainment that can be wasted if you just want to have fun.
Investment and instant multiplier effect is one difference that you have pointed out here. Yes on a longtime, bitcoin is regarded as investment but at no time will gambling be regarded as an investment but rather it could be regarded as profit multiplier system that is, the aim of gambling is for quick and fast money generation but whether this manifest or not depends on the winning and losing rate of the gambler. People also known gambling because it is as old as humanity. In fact every older youth must have known what gambling is but has a choice to follow up with it or not but same will not be said about bitcoin because it is still relatively new and many countries have not legalized it which causes its popularity not to grow on a fast pace.