The second-to-last point makes zero sense in this context. What makes you think that your browser is any more trustworthy?
And of course, none of this matters when you're running this software on a closed-source operating system - one which you, therefore, have virtually-zero ability to independently audit. So even if your programs are perfectly trustworthy, the underlying operating system has free reign to compromise them without you being able to detect it or do anything about it.
Probably the most surefire way of being actually secure is to drive to Calgary and pay Theo de Raadt to burn you an OpenBSD CD-ROM right before your eyes, then install it on your computer (and even this is fraught with danger; who's to say that Theo isn't going to backdoor your installation?). Virtually every other method of installing anything is insecure, whether you download the thing or have the thing mailed to you or what have you (the sole exception being to download the source code, manually audit it yourself, and manually hand-compile it to machine code - can't trust that compiler to not be compromised, after all). And on that note, you therefore still can't trust Theo's custom-made OpenBSD CD-ROM, since he very well might have compiled it with a compromised compiler, so now you have to take the OpenBSD source code and hand-compile that to machine code before you can do anything else.
And of course, none of this matters when you're running this software on a closed-source operating system - one which you, therefore, have virtually-zero ability to independently audit. So even if your programs are perfectly trustworthy, the underlying operating system has free reign to compromise them without you being able to detect it or do anything about it.
Probably the most surefire way of being actually secure is to drive to Calgary and pay Theo de Raadt to burn you an OpenBSD CD-ROM right before your eyes, then install it on your computer (and even this is fraught with danger; who's to say that Theo isn't going to backdoor your installation?). Virtually every other method of installing anything is insecure, whether you download the thing or have the thing mailed to you or what have you (the sole exception being to download the source code, manually audit it yourself, and manually hand-compile it to machine code - can't trust that compiler to not be compromised, after all). And on that note, you therefore still can't trust Theo's custom-made OpenBSD CD-ROM, since he very well might have compiled it with a compromised compiler, so now you have to take the OpenBSD source code and hand-compile that to machine code before you can do anything else.