The costs to subvert SGX are unfortunately far below millions. Probably hundreds or thousands after you have some one time research.
It is a viable additional client protection, especially against remote malware, software-only tampering (unless there are implementation bugs or backdoors), but not a viable server trust substitute.
It is a viable additional client protection, especially against remote malware, software-only tampering (unless there are implementation bugs or backdoors), but not a viable server trust substitute.