When is better to buy crypto, on pre sale or on ICO? When you buy on presale, you can get good bonuses, however when you buy on ICO you have a better gurantee not to be scammed.
You will gwt more coins or discount during the pre sale. However, investors during this stage takes more risk since there is a chance that the ICO will not be succussful or will not have enough funds to develop the project. I guess that is why pre sale investors get more token.
Also when the ICO finished, the price was dump unless you buy token at cheap price then you sell it at high price but it depend because some ICO don't release market immediately and you can sell your token together by some participants who get paid that can cause by dump.
I think it is good to buy when it dump because you can get more profit when it pump. Almost all token that are dump first then pump soon.