In my case, before I investing in any ICOs, I'll check their total supply first, then their whitepaper, then roadmap, then the team behind it, and the last but not least, their mission. I love an ICO with infographic pictures too, it makes me more confident to invest in it.
Ok,put it this way, I am selling you oranges. I have 1000 oranges and I will be selling 10 to the public.
Let´s say that I manage to convince 10 people to buy my oranges at 10 dollars each. I will get 100 dollars.
Now, since I have 990 oranges left and the market price is 10 dollar per each, then I have 9900 dollars in oranges, that is, my tokens are worth 9900 dollars.
Except that it is not true at all! I got 100 dollars and a lot of oranges and when the people who bought them try to sell them they won´t even be able to get 10 cents per each because there are too many oranges and they are not worth 10 dollars at all, even I scammed people into believing it.