A super-illegal drive isn't really useful for comparison. With moderate traffic you'd be lucky to average 60mph for the entire trip from SF to LA.

Regardless, I'm not talking about what's ideal or perfect; even if HSR could get me there in 2-3 hours, that's not a meaningful enough improvement over 3-3.75 hours to justify a $64B+ price tag in my book.

I am not sure how the price tag is relevant to you personally. If you build an effective network of High speed rail it ends up cheaper per trip which over time means the effective cost is ~0$.

I doubt they are going to succeed, but in other areas it has worked.

Averaging 100mph is unrealistic for I-5 most of the time. You'll get stuck behind cars doing 80 in the left lane while semis sit in the right, and that can last for miles and miles. I think things were faster in 2010-11, when the economy was slower, but I only drove it twice then -- even then, 90mph was more realistic.

Which is fine I guess? If I'm going above the speed limit I have no issues staying on the left lane if I continue passing other cars. I don't have to always make space for someone 30+mph above the limit (both legally and morally).

If you're only going 10 over just like everybody else you belong in the right lane.

Sure, on current infrastructure 100MPH is unrealistic in that area, but if they added more roads so you could do 100MPH nobody would call it high speed transit.

Honestly if they added a third lane to I-5, that would be good enough. At least from Grapevine to 152.

I regularly drive ~120mph+ in the empty expanses of Spain and elsewhere that isn’t America, and even I can’t average 100mph in that route in California.