Steam itself is totally safe to download from the official site - it’s from Valve, a legit company that won’t give you malware. The real issue isn’t viruses, it’s that Steam has thousands of games including violent/mature ones, plus kids can easily chat with strangers and access community content that bypasses any game ratings. Most parents think turning on Steam’s “Family View” is enough, but teens figure out the PIN by watching parents type it or just use the web browser to access Steam directly.