When you wrench for a living, it's tough to come to the same thing
Toughest by far was my first concours restoration. Swore I'd never do another one. Then my hobby became my job, did that for 5 years, took a 4 year break, then got into a different type of wrenching for another 17 years. No longer wrench for a living, and now I've got an awesome collection of tools and skills, and it's become a hobby again. I really enjoy doing what I want, when I want, how I want.
It's kind of a full circle thing. Sometimes I don't even look at my car for a month, other times I get up at 4am just so I can go out in the garage and mess with it before work.
As for high horsepower daily drivers, with today's advanced technologies, a properly planned and executed project could easily be a daily driver well up into the 800HP range, if not more. EFI, roller blocks, proper cooling systems, and liquids, cryogenics and metalurgy have done amazing things. Couple that with clutch & torque converter technologies (sorry I couldn't resist the pun), and drivetrain technologies, brake technology and basic car build quality, and this is very feasible.
Don't think so? Look at the tuner diesel trucks. Daily driven, towing 4,500 lbs ski boats at 700HP/torque. How much more abusive can you get, than a dumb ass drunk pulling his boat up a mountain?
What makes it real or not, is the skills required to build a complete package. That is what seperates the real builders from the parts hangers.