If a project holds that many tokens then it is difficult for me to trust them. This is not necessarily due to the fact that they might dump it in the future. Who knows that these tokens might actually be planned to be used for a newer project....

My reason for distrust come from the fact that the this kind of percentage holding is against the core philosophy of decentralization. Historically it has been shown that too much power concentration in one area will breed trouble for later. 

This is one of the areas where I am not comfortable buying in the project even when I see that it has a sound team and technology. Another factor is the fear of these tokens being scammed away from the project. Even if the team is good but they are still susceptible to scams and phishing and hacking like all token holders. One percent tokens getting stolen might hurt the project but thirty percent might kill it.