It's really a question of who you trust. There are lots of scenarios where you might trust the developer of a particular piece of software more than you trust

It's really a question of who you trust. There are lots of scenarios where you might trust the developer of a particular piece of software more than you trust the entire software stack running on your PC. This is especially true for a nontechnical / casual / grandma user, who has no hope of ever auditing or even having more than a vague idea of what's running on their computer at a given time, and probably is running (or at least needs to be assumed to be running) six different kinds of malware all the time. To someone like that, the PC itself is a hostile environment which they don't want to share certain information (e.g. their banking details, crypto keys, etc.) with. SGX allows you to ensure that. If you take on premise that the PC is not safe and under your control, but is instead hostile and compromised, basically an outpost of the Internet in your house, then SGX and similar start to make sense. For many people, their computer is always going to be hostile; it was never "theirs" to begin with, so SGX doesn't really cost them anything, and the ability to let a single application basically force its way down to the hardware and elbow everything else in the stack out of the way is an improvement over having to trust the OS, browser, etc. In a way it represents an abject failure on the part of the dominant OS developer (Microsoft) to produce a consumer computing platform that the average user can trust, as well as the failure of most other alternatives (e.g. DoD-style smartcards) to take off in the consumer market.