what can future blockchain developers and architects do to make blockchains safer and what should investors look for in a project in that safety aspect?
For developer/architect/contributor :
1. Choose cryptography/consensus method which is proven to be secure
2. Avoid making your own "cryptography", even if you're expert
3. Security audit your project/blockchain, few cryptocurrency skip this and ended up attacked with little to no cost
4. Think how much decentralization you want/need since you could gain more security/immutability if lots of people run full nodes
5. Never rush your development phase just since few security holes required rollback as fix which is controversial, such as ETH DAO
For investor : basically what they should do with ICOs