Because speculation always comes with big risks. And where there are risks, there will be scammers.
This is really a bad approach if you think the system is whole about scam, no brother this isnt right. Not only in bitcoins and crypto but in every walk of life, there are good and bad people who maintain or deform the values of that system. So we cant just label that system a bad one just because some people scam out there. Rather the system of crypto currencies are so amazing.
In a world full of deception and uncertainties it's always a good move to be protected from any harm. However, it's becoming hard to change the mindset of the people around to believe into something real. There's nothing wrong to take actions in this kind of trap, but I believe only us can eliminate this worst trend. We have to be guarded all the time, do investigation, and filter which is fake and original, by taking the appropriate actions.