Not a one ever infected any of the machines I did and do control, since about 1997 or so. The few times a security flaw was discovered the ‘nix coders released a patch amazingly quickly and nipped it in the bud.
I am happy to say that I have never had an infection of any sort while running Linux on any of these machines. I also never run any other OS while working online and have never been compromised to date.
The question was "So by running Linux, you're safe from infection by Trojan malware?"
Do you not know that a Linux system is just as vulnerable to this kind of malware as Windows, or do you know but carefully omit that piece of information?
You, personally, have never had an infected Nix box, but it’s not impossible to infect them.
The kernels of every major OS on the market right now (MacOS, Win10, major Nix kernels) are hardened to the point of being impenetrable. The majority of malware and viruses from from programs installed on those systems. It’s functionally impossible to infect the kernel of an Internet-connected operating system if you’re using a modern OS.