On ICO investing you will have to wait for several months like 3 to 10 months before the ICO is finished and you'll wait to 2 to 3 months more to get the coin in the market and there's no guaranty that you will make a profit, majority of the coins coming from ICO are down 50 to 90% and that was over a year of waiting.
on online gambling, if you play your cards right like when you have control on when to stopped and you have built a strategy, you can win over and over again and you can withdraw your gains immediately
I believe it depends on the individual. some people have passion for gamings with various reasons and they mostly consider investing in playing games or even in the games industry rather than ICOs while many others consider ICOs more important than gaming and therefore spend their resources as investors towards that business that gives them joy and ignites their passion. But if I am to choose amogst both of them, I will choose the ICO.