Yes, also If ICO were from the same sphere, it is better to choose the most promising project. But yes, better too choose what you understand
You could always go for multiple projects with different ideas, approach methods etc. It's actually safer since, statistically speaking, there's less chance that every single project goes down.
Yes, that's right. Besides, it's interesting. During this, you study different spheres, which could not have any relation to you in another situation.
