asked me in 2010 or so "what opportunities i saw in energy" i said well modular fusion, fission (though at the time i said small, off grid, which is how everybody starts, now there is interest in BIG) and energy storage. he went out and found and funded impressive companies before going back to YC and president. YC research was also something he did. a bunch of early funding of people like bret victor (my firehome roommate....) and vi hart and alan kay you can be pivotal in getting stuff going for a lot more things that people will believe possible or you'll ever get credit for, it's a good way to roll
Sam Altman deserves credit for YC's turn toward hard tech. When he became CEO in 2014 he went out and recruited companies doing stuff like airliners and fusion, and hard tech startups have been some of the best in every batch since.