It cannot be done.
All of it are just foolishness, stupidity and lack of knowledge which all are just the same.
Exchanges now are centralized, they are being hacked because of that.
Another is phishing which could be prevented if you did the right thing?
Scams? What kind?
All of this could be prevented if you are doing the right steps.
Exactly. Most scams or loss of funds are largely because of misuse among everyday people. They are not aware of how to properly secure their cryptocurrencies against hacks or theft by never leaving their coins in an exchange and doing several other practices. Because centralized exchanges have the most liquidity on the market, they are widely used worldwide. This brings a single point of failure, where centralized exchanges become honeypots for hackers. For people that are newcomers into cryptocurrencies, they could easily lose their coins by leaving them on an exchange.
However, all of this could be avoided by taking the necessary precautions to secure your coins. It's not decentralization's fault, but rather the lack of education among average people within the mainstream world. If everyone were to follow the right guidelines in securing their coins, then it'll become nearly impossible to get robbed. Decentralization brings unmatched security, but the greatest flaw of it is the user himself.
Nonetheless, I believe that there needs to be regulation in order to put an end to scams once and for all. Just my thoughts