If that's the case, how is the virus going to infect my computer unless I run untrusted code I downloaded on purpose? And if I'm doing that then I am accepting

If that's the case, how is the virus going to infect my computer unless I run untrusted code I downloaded on purpose? And if I'm doing that then I am accepting I'm likely going to get hacked, before and after Spectre/Meltdown, so how exactly are they making the situation worse?