Decentralization is a wonderful thing. There is no single point of failure, no middle man, only freedom.
But with great freedom comes great responsibility - and never before was this saying more accurate than these days. During last 2 weeks alone, Steemit was subject not to one, but to two phishing scams and a DDoS attack (which may or may be not related to the aforementioned scams).
In a centralized system you, as an end user, don't usually see all this stuff, because the centralized authority interferes and most of the time conceals this information. But in a decentralized system everything is out in the open. The beauty of uncensored creativity as well as the ugliness of greed and theft.
So, how do you fight scams in an open, transparent system?
The answers is found in the saying above: by assuming your part of responsibility. By taking extra steps to ensure that all your actions here are secure. Because if you rely on a central authority to "take care of you", to "protect you from the scammers", well, you may be in for a very disappointing outcome.
Don't get me wrong, there are quite a lot of "white hat" security savvy people in Steemit and many of them are working voluntarily for the benefit of the community. But most of the time they can come in only after a scam attempt has been consumed.
So, it's really up to you.
Step One: Inform And Stay Informed
The good news is that a transparent system can propagate any type of information - including information related to scams - way faster than a centralized one. Just like your body cells are fighting viruses by passing around information about the new virus signature, building defense structures and transferring the "plans" for this defenses to the next cell, that's how we, in a decentralized system, can fight scams and phishing attempts.
If you see a scam, tell people about it. If you've been subject to a scam, and didn't get caught, tell people about it. If you hear about a scam from a reliable source, tell people about it.
For instance, last week I've received a wallet message from 
WARNING: Phishing Scam By "@accounttransfers" On Steemit Via Direct Messages - Don't Fall For This!
Another example occurred this morning, when I got another wallet message, this time from a witness, 
SCAM ALERT and WHITE HAT COUNTER-STRIKE.
So, do tell people about. Do it fast.
Step Two: Stay Aware
Don't assume that everything here is all roses and dancing, because it's not. Stay aware and take care of your own. Look for messages you got from people you don't know, or from people who's account name looks like familiar names. Do your due diligence.
If an account seems strange, just look it up on a block explorer (steemd.com, steemdb.com).
Remember, everything is transparent here and all you need to do to reveal all the information about an account is to just look it up. It only takes a few minutes and it's free. Being scammed comes at a very high cost and it's usually non-reversible, so you do the math.
Here are just a couple of examples of phishing accounts:
And the list may go on and on.
So, stay safe and rest assured that the benefits of a decentralized system are, in the long run, outnumbering the problems.
Steem on!
I'm a serial entrepreneur, blogger and ultrarunner. You can find me mainly on my blog at Dragos Roua where I write about productivity, business, relationships and running. Here on Steemit you may stay updated by following me 
https://steemit.com/~witnesses
If you're new to Steemit, you may find these articles relevant (that's also part of my witness activity to support new members of the platform):