>> why build inefficient systems like Hyperloops and car sleds when we have tech that works at scale already > why build inefficient electric cars when we had

>> why build inefficient systems like Hyperloops and car sleds when we have tech that works at scale already > why build inefficient electric cars when we had a proved combustion engine that worked at scale before? The difference between these questions is precisely that the latter appears to have a good answer. What's the answer to the former?