Strength I see for Tesla is unlike the other car companies they don't have capital tied up in the legacy car business. Granted legacy is 97% of the market right now, but it won't be in ten years.
According to this link[2] gas peaker plans were 50% of energy installs in 2013, the best link I could find from a quick search.
[1] Interesting talk on this topic: https://www.youtube.com/watch?v=Kxryv2XrnqM
Yeah, I'd say it would not be unfair to compare future Tesla to a company like GE ($270B mkt cap).
Optimistic, but not irrational.
GE Healthcare alone employs >40 000 people and does >4x the revenue of Tesla today.
Maybe if Tesla merged with SpaceX and also with five-six other large companies you'd be about right.
Fair enough (though I'd think the oil & gas you mention would count), but look at any energy company today and you'll see similar numbers. Another poster in this thread compares to Exxon; similarly favorable.
You may not think Tesla will make it there, and you might turn out to be right. But those that do are optimistic; not stupid.