All these ICOs became successful only after a major investment and with a successful development and a good idea.
That's the real basis but development just came after the team raised the necessary amount.
Project which raised a big amount of money is not also a guarantee that they will be successful, that still defends on the market situation and how the team would handle the project, actually last bull run the ICO was so profitable, if they know how to manage the risk, they should convert their ETH raised to fiat for the future development of the project and volatility would not affect the project.
Mostly it's all about the matters of the team could making hype of the project, keeping people are always having a demand with the project and the price would be stable in the top. It's hard doing it because there are so many similiar projects and people will splitted their investment looking for which project could make a quick profits.