That's a little paranoid in method, but healthy caution vs unfounded paranoia is a vital distinction to make; one will keep you safe, while the latter may end you. In general avoid links off site on steam - you can still view content safely via a number of methods you should pursue to broaden your understanding. Mostly you want to avoid offering any information, or inputting any information; most of what is misrepresented as "hacking" is done via "phishing", which is just con artists using software to socially manipulate you to garner your personal information. A false link that would gather your saved or entered information would be hacking, and is quite a bit more sophisticated - I would never suspect that unless you are loaded (rich boi) did something involving vileness toward another person that might garner ongoing hatred and resentment. Generally people with the brain to do such things aren't going to waste their time, energy, and intelligence on mass-phishing or the general crimes more commonly perpetrated via STEAM.

Hackers are by far the least villainous and least of threats in consideration to the risks you actually face.

Steam has millions of accounts, and there's nothing preventing the use of a multitude of accounts by singular entities. The $5 restricted access for accounts does very little when stolen, abandoned, and otherwise repurposed accounts are easily attainable. Even if only a tiny fraction of the estimated criminal accounts are active on steam, it is still hundreds of thousands of accounts used for criminal activity on STEAM. There's no way to get this in hand unless the culture changes to demand it - Valve is going to keep taking money while offering as little as possible in terms of oversight and security; to be fair if they tried to fix it they'd have hundreds of thousands of complaints and protests. So more than likely it will just continue to be awful, unless it gets so bad that they are forced to do something significant.